I can only speak for myself, but my mentality was along these lines: I know that the Republicrat party is bad, and the only way to get someone into the whitehouse who will actually oppose the TPP is to elect an outsider who isn't in the uniparty club. This narrows it down to either Sanders or Trump.

Because I was still somewhat media influenced, it looked like Sanders was the only one who had a snowball's chance in hell at this. However, I understood what was happening immediately when he sold out, so I switched to Trump and proceeded to get redpilled on all the pedo shit. I already knew the Clintons were bad and running a mafia, but I didn't know how bad they really were. The only items I truly changed my mind on were tax cuts and global warming. (which are good, and a hoax, respectively)