Pick one (or more?) of the below depending on the person in question.
1) "He won't repeal *my* health care, just the brown people/black people/illegals/welfare queens" ect
2) "He doesn't have a real chance, and no Bernie, so I'm just gonna not vote/vote 3rd party, that'll show em"
3) "Both sides are the same, Trump might be a white supremacist, sexual predator and one of the biggest Wall Street-style crooks you can imagine, but don't forget about Hillary's emails and Ben Ghazi"
4) "I'm pretty damn rich so I can afford gud health care either way and I could really use some more money from those tax cuts"
From what I can tell the main source of regret post election has been related to 1 when a lot of senators in red states realized it's going to be hard to blame their citizen's loss of health care on Obama or some other Dem when they control all 3 branches and are up for job loss in 2018. It's also the main reason why there hasn't been anything passed yet. 2 is mostly Dem/liberal fall in love with personality related, 3 is fake moderate/fake critical thinking related, 4 is Faux News and their cronies related