Good for you, that's a the right choice. Be your own man.
I get it, man. They want everyone to step in line and vote to get Trump out.
You won't catch me disagreeing when people talk about horrible Trump is. And because of that, a lot of them (particularly on Twitter, but occasionally here as well), will just talk shit and name call and think they're right to do so.
I get it. You're scared of Trump. I'm scared of the status quo and the corporate bowing. Neither of those things change under either party.
Not asking, but OK. Talking about stuff like this: "They're one step away from being Republicans and most of them, without hesitation, would vote as such if Democrats actually moved left or a new leftist party emerged" or asserting that Biden would veto single payer, etc. It's precisely that kind of thing that keeps getting Republicans elected, which is the obstacle to any real left-ward move in policy, which is then justification for more refusal to vote (and voting third party is the same as sitting out).
Do modern democrats support any of the measures that I outlined as issues the left care about? I mean, you brought up the idea of Biden saying he would veto single-payer, and you're right, I exaggerated. He specifically said that "if by some miracle" it came across his desk, he would be worried about the cost and where the money comes from, despite the fact that we already spend a pretty tremendous amount of money on healthcare to begin with. He concern-trolled about raising taxes for the middle class and never mentioned tax-hikes for the wealthy as a way to help fund it. So no, he didn't directly say he'd veto it. You're right, I'm crazy to think the way he talked about it was utterly dismissive of the idea.
And yeah, your weenie scare tactics about "Republicans get elected because people don't vote for people they don't like" can fuck off. I'm not sitting out. I'm voting for who I think is the best candidate, not the most popular or not the most likely to win.
If Biden loses, it's his fault for not courting voters, not voters' fault for not voting for someone who doesn't give a shit about their causes.