The negative impact of mandatory diversity training:
According to a recent study published in the Harvard Business Review, mandatory diversity training programs in corporations not only fail to achieve their goals, they also have a negative impact on the hiring of females and underrepresented racial and ethnic groups.

After studying more than 800 companies across the country, Harvard sociologist Frank Dobin and Tel Aviv professor Alexandra Kalev found that companies made no gains in the proportion of white women, black men, or Hispanics in management and that the proportion of African American women and Asian American employees actually declined five years after the implementation of mandatory diversity training programs.

“We were quite surprised at first, because some of the most popular and costly programs — mandatory diversity training for instance — tend to backfire and this is what the quantitative data show,” Dobin wrote in an email to The College Fix.

“But when we began to interview managers to understand why popular programs don’t work, it began to make sense. Social scientists have long known that if you try to control people’s thoughts and behavior, they rebel. That’s what we find — programs designed to reeducate managers or stop them from discriminating directly tend to backfire,” Dobin noted.
I don't think it's merely people mulishly digging in their heels and being resentful of being lectured about how horrible they are. I suspect that if you are an annoying person constantly telling people that everyone else thinks women and minorities make inferior employees, they are going to weigh that evidence versus that of the clueless person hectoring them who claims otherwise, and then they are quite reasonably going to reach the conclusion that those people must be right, since you're observably an idiot.