Vote third party! It influences the major parties, who will REFUSE to act until they lose votes over an issue. Of course your candidate won't be elected, that's not the goal.
Check out the history of the minimum wage; Socialists have been fighting for such since the 1910s, and they are still fighting.
Check out the history of marijuana legalization; bOtH pArTiEs were delighted to throw hundreds of thousands of people into prison. The greens and libertarians have fought for legalization since the 1970s.
Why don't you know this long history? Because it's almost never reported on.
Vote for who you support, and remember that FORTY PERCENT of all voters are now Independents, the major parties have only 30% each and they will continue to lose voters, and they will get angrier about it every year.
You are not alone.