Who would benefit and what would keep them from being a casualty of their own making?
1) I don't know. It could be people who think they'll come out on top if there's a civil war, or it could be people who want to provoke the other side into reckless behavior that would discredit them.
Extremists on both sides see their membership rolls rise if the political climate becomes more heated and violent. That guy in Charleston who killed those people wanted to provoke a "race war." There are people like that in the world. There are also people who want to provoke a government crackdown on dissent.
2) Isn't it like that with all wars? People think they'll come out on top if there's war, but they may just get crushed themselves.