Because dummies like you would rather have Trump than the nice but imperfect lady! And it's not people like me and my political philosophy, I'm almost certainly to the left of you, at least economically. I think centrists are horrible. But if it's centrists or Trump? Where do I sign?
Nobody votes for the lesser of 2 evils, it doesnt work. Voters dont do that. It's not how human beings function. You can live in that real world, or you can live in your fantasy world where people will vote for genocide as long as there is somebody worse on the ballot.
I and virtually everyone talk to about this IRL vote for the lesser of two evils. We are all human beings, and we function this way. We prefer the non-fascist option, as a general rule, and where there are only two realistic options available we are not overly squeamish about the other option.
And the vote was NOT for or against genocide. From your perspective, the vote was neutral on genocide (i.e. both parties supported it), but it was about whether to have fascism in the US, which you seem to have helped with your voting decision. Congratulations, I hope you like it.