But why not you? Why not try? Have the courage and morals and try to make a change. At the very least, stand up for your beliefs. Get fired for going to battle against the evil in the world. You might find allies along the way and win.
I am generally against the idea that a long, open campaign against a specific more senior individual is likely to succeed.
Often times the supervisor of toxic managers are very aware of their toxicity but accepted it either as a tradeoff or in some cases actually like it.
A lot of these guys will burn it all down on the way out too.
I worked in a team that was having 40% annual turnover for 5 years. In the final year the toxic guy 3 levels up C (A->B->C) forced my boss' boss B to fire my boss A, then fired the firer B a couple weeks later. Finally when this was all over C himself resigned a couple months later.
Given his seniority and the time it takes to find a job at his level, he knew he was going to leave when he forced the final culling. He let A&B stay around for 5+ years and then when he knew he wouldn't have to face the consequences.. he whacked them and resigned.
Apparently the replacement for C is worse.. because the CTO all the way at the top is.. into that.