This is true for national tickets but local and state-level you can totally sway the outcome. I think that's part of the problem - nobody gives a shit until we're voting for president when simple things like "do I want my ambulances to be run by a private for-profit corporation" are things that directly impact your community. There's also the "old people constantly vote against libraries" problem which young people are uniquely positioned to solve as well as the "I would like to starve my local school district to give rich people vouchers to pay for their Montessori programs" that can be overturned simply by having renters outvote homeowners.
They want you to despair. Despair and tenaciousness are about to be their only weapons.