Studies generally show the economy does better under Democrats than Republicans, in measurements of CPI, GDP, job growth, and unemployment. Republicans however have a massive propaganda machine that has gaslit the country in believing the opposite. Frequently this is backed by short term plays that make things "feel" better but cause significant long term problems. Like a CEO firing the QA team, line goes up this quarter and by the time the consequences arrive they're gone and blame the next guy.

They're operating under a lot of propaganda, and no understanding of economics. They're ignorant of the fact that Trump inherited the economy that Obama fixed, which is why at the time under Trump things were better. They're ignorant of the fact that Trump fucked everything up with his handling of the pandemic, previous tarrifs, and in turn fucked the economy up on the way out. They're ignorant that Biden was trying to clean up Trump's mess, and instead assign blame to Biden.

And every after all that, there is still the added fact that the president doesn't directly control the economy, and has limited options. But that doesn't matter to them. They've been sold a simple solution to a complicated problem.