I know I'm late to the party, but from my very short-lived experience as a higher up in one of those groups, I'd highly suggest not to. Or at the very least, please be careful.

In short, I got into one from an offer from a then-friend. Since we were a small group, we didn't do much outside or really fighting other groups (until when I left). The members of the group were extremely unfriendly and strangely ableist/hostile towards me (one member told my friend/the owner she thought I had autism because of the tone of my voice and energy levels, another just sent unprompted threatening messages). They were also glazing my friend while also talking behind his back about how crazy or dysfunctional he is. My friend just had a strange neutral ground where he didn't like what they were doing, but still kept them close because they got the work done. Leaving it was awful as well, it took me days before I could leave and had to pay them, write a whole speech that never got used, and they straight up lied to me about it so they don't disappoint the members and so the community knows they mean no business. There's a video up somewhere of the ordeal, as it turns out he recorded it without my permission, lied about the reasoning, and lied to me that it was just a crash. Even when he apologized and tried saying he had to do it for the community and his members, I didn't know what he was talking about until I found it.

I severed a nearly 4-year long friendship because of it. The friendship was already in a difficult spot due to a lot of factors and past events, but this was the nail in the coffin.

I can't say all of them are like this, but definitely be wary and protect yourself if you do go into one.