Voting and Self-Interest

My TwitFace, or Facer, or LockdIn or whatever they call it, friends and 'quaintances, with increasing frequency seem to be deriding other people for being "stupid" enough to consistently vote against their own self-interest.

Forgive my ignorance, but doesn't any decent person regularly do things against his own self-interest?

Isn't one, as a Christian, or an enlightened secularist, supposed to do the right thing, not the thing that is most salutary for ones bank account or social standing or comfort?

It's a sad argument to be making, and it says more about the critic than the person casting the vote.