People like to do this because it's simple, but it's so unrealistic that it's basically a fairy story in terms of explanatory power.

You have to take account of warring internal factions.

True. In that sense the voters have self decapitated. I can’t understand how the Trump administration still has support from 40% of the country (per polls). I could understand voting for him due to some issue a voter has strong feelings about. But now we have seen it all play out and it’s a disaster leading to national ruin. And there is no talk of impeachment, trials, and accountability for everyone in his circle. So I guess that 40% DOES choose to self decapitate.