Do you know why social security is inviolate, and no one from either party will ever do anything to stop payments? Because old people vote. If you (and people like you) don't vote, you don't count, and no one will ever listen to you.
Voting increases the strength of your demographic, and then shifts the political allegiance of that demographic very slightly towards your views.
In regards to this argument, a single vote has no value because the outcome of a single mandate election of this scale is never determined by 1 single vote. The outcome would remain the same with or without your vote. That is the point.
You bring up issues and demographics. Same rule applies. The attention given to your demographic is never affected by 1 single vote unless it is the single vote that causes the politician to focus attention or turn his/her back. This is obviously a gray area that can't be measured.
Do you seriously believe that young people would, as a demographic group, generally vote together to disband social security?
I don't think there's an old person vs young person divide at all. There's plenty of divide between conservatives, liberals, communists, libertarians, etc, of all age groups.
If the young people had something like this, the drinking age may still be 18 instead of 21.