That’s easy:

2016: Our politicians are on the take and out to lunch. We just disagreed on what to do about it.

2024: Cognitive dissonance. It’s hard to admit that you got conned that bad (eg starting with the insurrection, which really is the only issue. You can’t trust anybody who thinks it didn’t happen or doesn’t matter - arguing with them is like arguing with a Flat Earther - pointless)