It's sad seeing that stuff. Hating people based on race or ethnicity is ridiculous and dehumanizing. To answer the question in more detail, though, I think it is important for the people who disagree to acknowledge the things that start people down that path. Broadly, I would say those are:

• Noticing that all of the typical liberal identity politics rhetoric about white men could just as accurately (and in some cases more accurately) be applied to upper-class Jewish people. Overrepresentation in major industries, responsible for many major cultural works, insular and privileged groups that sometimes promote each other, etc.

• Anti-white attitudes are largely tolerated, even though anti-Jewish attitudes are not. For example, Nick Cannon got in hot water for "anti-semitic comments," even though if you read his actual comments he used the exact same dehumanizing language about both white and Jewish people, suggesting that they are inherently inferior and evil.

If the mainstream left, center, and right do not allow discussion of these topics, or do not allow white people to express grievance about anti-white attitudes and be taken seriously, that will tend to push those interested in "forbidden" topics to more radical circles that welcome them.

Personally, I view the solution as abandoning identity politics, and pushing for more dignity for lower class people of all races. Blaming "white men" for society's problems as though all white men are in charge and have an ideal society for them is obviously false. Small groups of people in positions of power will always find ways to enrich and benefit themselves and people closely associated with them, but this rarely trickles down to ordinary people in meaningful ways. A white guy who owns an oil company or a Jewish guy who owns a movie studio don't help your regular white or Jewish neighbors any more than the existence of Oprah helps your regular black neighbors. Sure, class is not the only problem in society, but all of our problems could be expressed as "society does not respect ordinary people enough."