I can not say too much about mentioned militias, but yea, I agree that lot of organized armed group started like “freedom fighters” or “defenders” or similar, and at the end it was all about power and resources.
And lot of them were absolutely sure that they are doing right thing.
Simply I would love to keep my right to defend and destroy everybody who might take my liberties some day, including those who are (or state to be) defenders of that liberties.
It is quite possible for armed group to do lot of bad things in the name of the “cause”. I agree that there need to be some kind of control over the folks who are trying to control us, and it needs to be unwavering, but very often it corrupts (spoil).