Because he got the highest number of votes in history and had a strong base. Unfortunately people didnt go the poles. Political apathy, tarred and feathered by the right wing press (Yeah I REALLY believe the paper that supported facists got it rught by claiming the guy whos consistently been on the right side of history is an anti semite because he went "Yeah Israel...your...uhh...being a tad shitty there guys") including at one point a ludicrous case of them claiming he was a soviet era spy.
I saw 18 year olds on facebook screaming about communism and the Soviet union as if they actually knew what the **** they were talking about.