What is the mindset that criticizes the Democrats for being too right wing, and then lets the Republicans win?

I keep seeing this on Reddit. Usually it's something like, "If Biden doesn't forgive student loan debt, I won't vote for him. Then the Republicans will win, and it will be all his fault!"

I'm trying to understand how these people can be serious. If Biden loses because progressives are unhappy with him, that would be equivalent to progressives choosing a republican over Biden, right?

Help me understand the logic of preferring a Republican, because the democrats aren't left wing enough. Is this some weird "Went so far left that you came back around on the right" sort of thing?