The left wants civil war, that's the truth of it. They think they're fomenting a Marxist revolution and the fruiting of their dream to make America a clone of North Korea, but in fact they are just sparking civil war. The 21% can't win, all they can do is create chaos and bloodshed.
For many of them, I think that's the ultimate goal.
No more than the fringe Militia groups. Most of the OWS are a bunch of scared college kids that are looking out at a fairly bleak future after they were promised that if they worked hard, got good grades, went to a good school, and played by the rules they'd be ok. They're seeing the end of the American dream, and don't have a clue what to do about it.
When they turn violent, you deal with them. Until that point the best thing to do is to recognize they're a symptom and try to get at the cause.