The police are on the side of the people who control their paychecks and pensions.
As others have mentioned, these are small groups. How do they grow? There is no majority support for their actions, at least not where it counts. Is California going to secede? This sort of tactic has succeeded in the past by having a supportive media that controls the narrative.
They do not have that overwhelming support in the media anymore. Yes, they have the Establishment media (which is being discredited even further) and more partisan media on the net.
I do not think they have enough to foster a mass movement, and they do not have the troops to do it on their own.
Bank robberies, identity theft, some property destruction, a few assassinations. Sure, could happen. But you do not make a revolution or a Civil war out of that.
We had far worse in the 70’s, with a more supportive media on their side (almost no conservative media), and they got nowhere with the violence. It was the media that got the Left elected and radicalized, not the violence.
I think the key thing is to go after their sources of funding. The radicals get funding from Soros and various foundations. The radicals on the streets are just pawns for the elites. As long as elites are able to provide funding, there will be an endless supply of radicals.
It's like with terrorism. As long as there is funding, and a training base which uses that funding to turn out radicals, there will be an endless supply of terrorists, drawing us into a futile game of whack-a-mole.
The key is to identify the sources of funding, and go after THEM. No matter how wealthy, powerful, or "respectable", go after the funding sources.
One step would be to terminate government "research" grants going to radical professors. We do not need to fund research into "transgender influences in the music industry". Just cut out all those grants.
A next step is to roll up the people who organize and fund the "Black Bloc" groups, the BLM groups, etc. Use the laws that were used to go after the Klan, and make them liable for the actions of the groups they give funding and support to.