Change to something else, elaborate below!
Given X votes, a competitor should vote for themselves leaving X-1 votes (normally 0) for other competitors. Spectators are able to use the full X votes on whoever they like, giving the competitors an unfair disadvantage personally.
In my opinion, competitors should be banned from voting on themselves, enforceable by switching voting to Google Forms or somesuch. Email address / forum name could be used to confirm identity, and it's no harder to cheat there than it is here.
However this might be a lot of effort for limited return.