"Why are people so much smarter at making personal decisions than deciding how to vote?"

Jaltcoh points to Bryan Caplan's discussion of self-correction, which keeps us from dumb decisionmaking in our personal affairs, but:

In politics, self-correction doesn't save the self-corrector a dime.  Voters who self-correct live under the exactly same policies as voters who don't self-correct.  The result is a dire shortage of self-correction - and reliably ridiculous policies no matter who wins.