Modern police and military gear is so advanced that revolution is unrealistic.

It does not help when part of the military sides with the revolution. Which happened to some extent in just about all of them. It’s never just normal people against the army. Soldiers also have families suffering just like the others. They also see what happens to them when they leave the military and become part of the underclass again. There is a spectrum between not following orders efficiently to just ignoring orders and then open mutiny.

Maybe. But a modern revolution also doesn’t need physical violence.

People in power only have power in so far as others believe and enforce it. The emperor has no clothes.

The gear generally requires an industrial base to keep it functioning. Given what was in SmarterEverDay's recent video about a barbecue cleaner, where so much of it ended up being imported despite their efforts (including chain mail!), I think in the event of another actual civil war, the USA would struggle to self-maintain any weapons more advanced than what you had in what is now "the" Civil War, and would be dependent on the whims of whichever foreign power wanted to support whichever sub-group.

If they want to try their hand and unleash the first American genocide in history, that may be the cost for people to wake up. too many cameras and live uploading about to bury hundreds, maybe thousands of citizens being shot down in cold blood.