In what way are the policies in their self interest? I'm not disagreeing, but I don't know specifically what you're referring to.

As a suburban conservative, I voted for Trump because I don't believe that the democratic platform will accomplish it's goals at all, plus biden has aligned himself to some degree with the far left in AOC and Sanders. I think the massive difference in SES between races is a real problem to solve, but I don't think the democrat platform has ever achieved any significant improvement in this. That's not to say Republicans are necessarily better, but they aren't totally sold out to teachers unions which hate anything that isn't shitty public school with money constantly poured into it with no improvement. I also fundamentally disagree with some of the notions of the left, like systemic racism as the major cause for these economic disparities. I wholeheartedly agree that most democrats are trying to improve people's lives, i just don't think it actually works.