Talking about race in America often brings strong emotions and harsh feelings. What is going on with that? Why does race and racial discussion complicate American discourse? I believe that this is true because 1) white supremacy has been tied to prosperity; 2) White America is ashamed of this history; and, 3) White Americans may fear its own mediocracy.
White supremacy is tied to American prosperity.
The purpose of Jim Crow (1886-1966) laws and policy in America was to ensure that all wealth, prosperity, and power would be exclusive to non-blacks. Hence, the definition of "white" was in constant flux. New immigrants and other individuals actively pursued inclusion into the "white" category in order to gain access to its benefits.  But the definition of "black" was well established. The "black" or "negro" or "colored" assignment included anyone with 'one drop' of 'black blood.' Those individuals would not be eligible for American prosperity. In some instances, upon finding that a person or family had black ancestry their wealth was removed or commandeered.
Many immigrants were also disenfranchised if they were suspected of having negro or black blood. However, because of the diverse immigrant community and the "passing" of lighter skin blacks, it became more and more difficult to keep wealth away from the black community.
America is simply ashamed.
The truth be told, every citizen in America has contributed towards the foundation of our county. In order for our country to effectively take advantage of its resources, manage their distribution, and acquire the luxury of a collective effort, the entire country had to work in unison. In other words, American prosperity has been a team effort. However, White America has hoarded the benefits of America's prosperity by use of an unfair racial regime. The White majority has openly taken advantage of the collective efforts of the American community, and redirected benefits to itself.
However, the exclusion of Blacks from America's prosperity became difficult to ignore and even more difficult to control.  As Blacks were able to retain the rightful proceeds from their labor, White America became more aggressive and violent in taking that prosperity away. In fact, White America found ever increasing ways to benefit economically from Black subjugation. As long as White America distinguished itself from the others, the devaluation of Black neighborhoods bolstered the valuation of White neighborhoods; the devaluation of Black education bolstered the valuation of White education; the devaluation of Black families bolstered the valuation of White families; the devaluation of Black lives bolstered the valuation of White lives, etc. However, the diminishment of Black Americans also resulted in lowering the standards of White Americans. As the decades passed on, white supremacy began to erode the White community's desires towards self betterment.
Fearing White Mediocracy.
Martin Luther King once said he longed for the day when a man would be judged not by the color or his skin but by the content of his character.  This statement was an indictment of White
America's failures - the lack of core ethical values of honesty and integrity, respecting others, taking responsibility for one's actions, being fair and just, and being someone who promotes love and compassion in others.
America's southern leadership worked overtime to distract from their insidious attempts to sustain Black subordination by emphasizing a non-humanity, criminality, simple mindedness, and overall undesirability branding onto the Black community. However, these attributes eventually became that which more squarely defined Whites in America than its intended target. As more people interacted with Black Americans, and witnessed scholarly superiority, virtue, moral character, and talent over the decades, the arguments of the Southern Gentry became less impactful.
The 2016 election was a pivotal moment. The character of America's White majority was exposed. America had nurtured a group of individuals who had given up on seeking excellence but rather instead relied upon brute force and bullying to maintain its power structures. The sad truth was that our country continued to reward white mediocrity and, thus, limiting the drive and imagination of white people. People of color were being forced into limitations of success in order to deliver on the promised white supremacy.
Ultimately, White mediocrity harms us all and subjecting Blacks and other racial minorities to a negative racial frame without acknowledging the deterioration of the White community put the entire country in peril. 
This is why is it difficult to talk about race in America. There is too much reliance on race based prosperity, shame, and petulance. Our country is trying to overcome this horrendous shortfall; however, the first step requires each of us to be honest about how we got here.
 It was never the case that a white asset-based middle class simply emerged. Rather, it was government policy, and to some extent literal government giveaways, that provided whites the finance, education, land and infrastructure to accumulate and pass down wealth. See https://www.marketwatch.com/story/heres-why-black-families-have-struggled-for-decades-to-gain-wealth-2019-02-28.
The decades of the Jim Crow era, Tennessee adopted a one-drop statute first in Tennessee in 1910 and in Virginia under the Racial Integrity Act of 1924 (engaging the passage of similar laws in several other states). Texas and Arkansas in 1911, Mississippi in 1917, North Carolina in 1923, Alabama and Georgia in 1927, and Oklahoma in 1931. During this same period, Florida, Indiana, Kentucky, Maryland, Missouri, Nebraska, North Dakota, and Utah retained their old blood fraction statutes de jure but amended these fractions (one-sixteenth, one-thirty-second) to be equivalent to one-drop de facto. There have been failed legal attempts at the federal level to dismantle whiteness as well, Ozawa v. United States 1922 is an example. By 1925, almost every state had a one-drop law on their books, or something comparable. These were the laws that gave power to bureaucrats like Walter Plecker of Virginia, Naomi Drake of Louisiana, and others who insisted on labeling families of mixed ancestry as black. Before 1930, individuals of mixed European and African ancestry were classified as mulattoes, sometimes as black and sometimes as white. The main purpose of the one-drop rule was to prevent interracial relationships and thus keep whites "pure." In step with this concept was also the assumption that blacks would be "improved" through white intermixture. Despite the one-drop rule being illegal (ever since the U.S. Supreme Court in 1967 overturned the Virginia Racial Integrity Act), as recently as 1986, the U.S. Supreme Court allowed the ODR to stand by refusing to hear a case against Louisiana’s "racial" classification criteria as applied to Susie Phipps (479 U.S. 1002). See https://aaregistry.org/story/the-one-drop-rule-a-brief-story/
Elmore Bolling, whose brothers called him Buddy, was a kind of one-man economy in Lowndesboro, Ala. He leased a plantation, where he had a general store with a gas station out front and a catering business; he grew cotton, corn and sugar cane. He also owned a small fleet of trucks that ran livestock and made deliveries between Lowndesboro and Montgomery. At his peak, Bolling employed as many as 40 people, all of them black like him. One December day in 1947, a group of white men showed up along a stretch of Highway 80 just yards from Bolling’s home and store, where he lived with his wife, Bertha Mae, and their seven young children. The men confronted him on a section of road he had helped lay and shot him seven times — six times with a pistol and once with a shotgun blast to the back. His family rushed from the store to find him lying dead in a ditch. The shooters didn’t even cover their faces; they didn’t need to. Everyone knew who had done it and why. “He was too successful to be a Negro,” someone who knew Bolling told a newspaper at the time. When Bolling was killed, his family estimates he had as much as $40,000 in the bank and more than $5,000 in assets, about $500,000 in today’s dollars. But within months of his murder nearly all of it would be gone. White creditors and people posing as creditors took the money the family got from the sale of their trucks and cattle. They even staked claims on what was left of the family’s savings. The jobs that he provided were gone, too. Almost overnight the Bollings went from prosperity to poverty. Bertha Mae found work at a dry cleaner. The older children dropped out of school to help support the family. Within two years, the Bollings fled Lowndes County, fearing for their lives. See https://www.nytimes.com/interactive/2019/08/14/magazine/racial-wealth-gap.html
 Blacks have been beaten and killed because of their race, denied the right to vote and prohibited from living in certain neighborhoods. They were and still are discriminated against in the workplace and prevented from earning fair and equal pay. See https://www.washingtonpost.com/business/2020/10/30/black-americans-reparations/
 Martin Luther King delivered the "I Have a Dream" speech at the Lincoln Memorial's steps in Washington on Aug. 28, 1963, King delivered his speech to a quarter of a million people gathered for the March on Washington for Jobs and Freedom.
 Ijeoma Oluo’s new book, Mediocre: The Dangerous Legacy of White Male America (Seal Press, 2020).