It happens another way usually - in libertarianism anything non-voluntary and any violence is bad. The ideal is a society with involuntary violent interactions being minimal.

First, just like with Bolsheviks, ends may justify the means (let's build a totalitarian state which will fight capitalism, imperialism, conquer all the world and then make communism).

Second, and more often, different kinds of violence are not so different for a libertarian. As in - a normie might agree that they owe something by social contract that they hadn't signed and can't refuse. For a libertarian that's bullshit, and the legal systems built by non-libertarians don't allow them to argue their point - somebody else decides for them and says they are obligated to obey. ("Sovereign citizens" are basically libertarians who believe in proving a libertarian position through normie laws, which is nonsense, you can't win by rules defined by your adversary.) So "if there's going to be violence, then let it be our violence to our ends".

From the libertarian point of view the world is fascist in general. So they (libertarians gone violent) are trying to change it to good, while playing by its rules. It's sort of a revolutionary logic, which, again, is similar to that of Bolsheviks.

so they can’t imagine a situation where they aren’t the one with the boot or the one being stomped on

They can imagine that pretty well, but from their point of view they sort of already are expected to be stomped on in a non-libertarian world.

I hope I've explained it well.