There are two components to this question. Did many in the working class feel that Democrats had abandoned them? And is Trump’s economic policy actually better for the working class than Harris’s? I think the answers are “yes” and “probably no”. However, voters don’t listen to economists. If they’re not happy with the status quo, they vote for disrupting the status quo even if experts tell them that that’s a bad idea.

I suppose Sanders thinks that the working class would have supported a Democratic candidate who proposed a leftward (as opposed to Trump’s rightward) disruption. My guess is that that isn’t true and socialism is still a dirty word in America, but who knows?