Edited for clarification:
I’ve seen it postulated that social injustices are caused by wealth or income disparities. So, if we address the latter, we'll address the former. That reflects a fundamental misunderstanding of the relationship between social and economic justice.
I'm sympathetic to what many dismiss as "far left" points of view, but this is one major issue that many leftists get wrong. In fact, you might even say people who make the above claim have it completely backwards. The fostering and exploitation of bigotry (along with race-based voter suppression and gerrymandering) is what enables Republicans to win political victories, which leads to right wing economic policies being enacted. Those policies hurt more than anyone those who are already most oppressed. Then, the wealth gap between white individuals and persons of color is justified using various stereotypes.
This has been the case since the founding of the US on the genocide of one people and the enslavement of another. Remember, race is a social construct. And "whiteness" (along with its supposed superiority) was an invention borne out of the desire to prevent a united front by all poor, oppressed people. Whites would be indentured servants with light at the end of the tunnel, while Negroes would be kept in bondage. Poor whites would be thrown a bone (and a whole lot of propaganda), enough to make them feel superior, enough to make them feel like they had more in common with their oppressors than their fellow oppressed.
Social Security (initially), the GI Bill, access to housing and other investment opportunities, the right to vote, access to higher education, access to employment with a decent wage, access to a fair trial and so much more was essentially denied to persons of color and women. Those injustices (even those that were seemingly resolved) continue to impact the present, including the wealth gap between white households and black and brown households, between men and women. Therefore, a rising tide has not historically lifted all boats. Ta-Nehisi Coates makes
"The Case for Reparations."
This is why social justice victories (legalizing gay marriage) and breaking barriers (first Black POTUS, first woman POTUS, first transgender state legislator, etc.) constitute more than mere symbolism. They are cracks in the facade, and crucial steps toward addressing economic injustice.
Much has been made of the *white* working class, or even white working class men. Democrats already do better than Republicans among the working class. In saying Democrats shouldn't go out of their way to appeal to *white* working class men, the point isn't to denigrate that subset of the population. The point is that the Democratic Party platform should already appeal to the working class. And, for the most part, it does, based on exit polls following every election.
Why speak specifically of *white* working class folks? We all know why. Either it's because there's this assumption that only white people work (horribly racist and obviously false), or it's because a certain portion of *white* working class folks are voting based on factors that have nothing to do with candidate positions on wage stagnation, workplace safety, health care, equal pay, paid family leave and all of the other issues that should matter to the working class. If that's the case, and I think we all know that it is, what does one suggest Democratic candidates do?
Should Democratic candidates not talk about criminal injustice, the race-based "War on Drugs," race-based voter suppression, a path to citizenship and the fact that US policy has been a driver of immigration all around the world, reproductive rights, equal pay, a culture that suggests sexual assault is tolerable, and so on? If not talking about those things, or - worse - taking the opposite position is what it will take to win over a certain subset of the population, then that's just too bad. As Dr. King said, "Injustice anywhere is a threat to justice everywhere." Just as some rich folks recognize the danger of extreme economic disparity, we should all want less disparity (in terms of wealth, criminal justice, medical care, housing, etc.)
between white folks and persons of color, between men and women, between gay and straight. Get on board with Democrats or lose, because ultimately "the arc of the moral universe bends toward justice."
So, in summary, going back to the invention of race/whiteness, the fostering and exploitation of bigotries has enabled economic disparities in the US. Economic disparities aren't what enable racism and sexism, though economic disparities are used - after the fact - as justification for social/cultural wealth disparities (again, stereotypes are used to justify the wealth gap between black and white households, for instance). Racism and sexism are what enable economic disparities. Whiteness and patriarchy had to be invented as a means to divide and conquer.
We must address racism (including xenophobia) and sexism head-on. If we don't, there's no hope of substantially redistributing wealth or opportunity. A common response to what I’ve written is that “we must fight for both economic and social justice” or that “it’s not an either-or situation.” Of course it isn’t. Of course Democrats and all people of conscience should be fighting for progressive taxation and closing tax loopholes, paid family leave, universal health care, ending imperialism, and so on. My point, though, is that right wing economic viewpoints survive and prosper precisely because of bigotry. Absent racism alone (to say nothing of other forms of bigotry), the Republican Party would cease to be viable.
Liberals often lament that millions "vote against their economic interests." Lament no more, as the reason has always been quite clear. The reason is those millions are voting *for* their perceived cultural/social interests.
And we must recognize that a rising tide is not sufficient. Measures must be taken to reverse history, so to speak. A good place to start:
https://policy.m4bl.org/platform/.
Lastly, a message for the young folks and others who are hoping for a viable left wing alternative to the Democratic Party in this 2-party system of ours. The first step is ending the viability of the Republican Party. And we do that by significantly diminishing racism, sexism, heterosexism and xenophobia (because that, and not right wing economic policy, is what's keeping the GOP alive). In the meantime, you need to support the only viable party that stands in the way of fascism. And you need to recognize that addressing social injustice is key to addressing economic injustice.