If you live in a swing state, you have to care about the winner. If not, it won’t matter anyway so vote Stein no matter what. Hell, vote Sanders if you feel like it.
Massachusetts, New York, California, etc. (Is it bad that I envision you living in such a place?) won’t be anything but blue on election day, so vote your conscience. The left has a long history of disappointment, but if you think now is the time for effecting real change, good luck to you.