Your "magic button" choice, if you will excuse me, is a reductio ad absurdum.

Not at all. It merely illustrates that it's not entirely unreasonable for people to support a bad candidate - even a really bad candidate - when electing that bad candidate will be better than the alternative, from their perspective. For many people within the base of either party, even the very worst candidate from their party will be better than an average candidate from the other party. Because while it matters who the President is, it also matters a lot what party the President is from. The latter is far more determinative of appointments (especially to the judiciary), Executive policies and priorities, and a host of other things big and small.

Trump's three SCOTUS appointments were consequential beyond description. In hindsight, for someone who is a strong progressive, there is probably no Democrat bad enough that it would be worth ever have been worth having a Republican win in 2016 rather than that Democrat. Had a Democrat - any Democrat - won in 2016, the things that progressives care deeply about would be far more protected and achievable than they are today: voting rights for minorities, fighting climate change, student loan forgiveness, abortion and other reproductive rights, environmental protections under the CWA, and a host of other issues would face a completely different environment than they do now.

Albaby