Most gulag prisoners were not political prisoners, they were common criminals. Most of them also got out after serving their sentence.
Believe it or not, but there are more than two parties that run candidates in US presidential elections.This shouldn't need to be explained to you.
No one is making the argument that you have to agree 100% with whatever politician/party you're voting for. And where on earth did you get the "write in yourself" thing from, that's an even more ridiculous strawman.
Bernie is a liberal