The problem is Russians are too afraid to turn on their motherland because "reasons" but that is exactly what has to happen to end the war. Hard to take medicine is indeed hard to take at first, but things are not getting better without it.
yes if you could magically organize 10_000 people they could overthrow anyone. But organizing is hard. Starting from a fact that they need some secure comminution channel, and the government fights VPN quite actively. How would you reach these potential people? You could do sort of broadcast a public message "if you don't like tsar let's take a walk tomorrow" but this signal would also be received by the police, so they can prepare. And we don't have the beautiful gun ownership culture of America.
And if you do something alone you just perish in prison.