Re: accuracy of polls. They're more accurate than you guys give them credit for. They're certainly not definitive, but they're a very, very good measure:
Though I agree that the national attitude right now doesn't really matter because lots of people will change their minds between now and November.
I think the reason it may not seem like that many people support Clinton is because a large chunk of people that do (particularly in liberal areas) only support her because she's running against Trump. It's like a bitter pill kind of support, not a "we really like this candidate" kind of support.
That's my reasoning for supporting her. If trump wasn't so godawful, I'd sit this election out like I did the last two(tl;dr I think of Obama as a near war criminal and someone who read 1984 and went "I want to do this.").
So, yeah, I'm voting because I don't want my rights as a minority and a woman stripped from me. I'm LGBT(amongst other types of minority), and given the way the conservative wing of the country's been talking about us lately, I'm getting fuckin' proactive on this shit. I am afraid of death squads 20 years in the future. Trump wouldn't enact them, no, but he'd open the fucking door with his policies and the people who he would pick.
Edit: Clarified myself a bit.