...because they might win? Its a two-party system like it or not.
I don't like it, so I would rather do anything I can to show that I don't like it.
There's a difference between doing anything, and doing nothing.
Well, if you don't like it, you could work to fix it -- which, at the state level in states that have provisions for citizen ballot initiative, doesn't even rely on gaining support from those elected under the present electoral system.
Regardless of the letter beside the person's name, money talks & shit walks. Either party (nationally, on the whole) could truthfully be described as "Centrist-Corporatist".
I think its probably more accurate to say that one is Center-Right/Corporatist and the other is Far-Right/Corporatist.