I blame the whole “voting changes things” culture. We tell kids that voting and politics means something and then when they learn how it actually works they get disheartened.
If we lower their expectations I bet they would vote more. Drop the idea that government will be responsive and filled with intelligent statesmen. Forget about any sort of relief or change. Vote for the one who will make politics boring. Vote because these idiots don't know anything and couldn't govern their way out of a paper bag.