A vote legitimises the government. By voting for someone you signal that you approve of their politics. A vote is very basically you signalling that you support a specific candidate. That's just what a vote is.
"Oh but I don't actually support him, he's just the least bad" Do you think Joe Biden is going to go door to door to ask wether your vote for him was a "real vote" or just a "please not trump" vote?
It doesn't matter what you feel about the candidate you're voting for, it matters that you're voting for them. That's what they count.

It doesn't matter what you think your vote is, what it does is support a candidates claim for power and subsequently legitimises that power. The US constantly uses the fact that it is a "democracy" (never mind the fact that it isn't, since popular vote doesn't matter) to legitimise it's foreign and domestic policy. Your vote aids them in doing that.

Anyway I've blocked you because I don't discuss basic politics with people who votes for genocide.