Back in school, a good friend of mine fell in with the stereotypical bad crowd.
I tried everything imaginable to get him out by explaining why the group had an awful reputation, how badly they treated members, and the dangers of ‘being on this path’.
I wasn’t alone in realising the futility of this.
Criticising a group on which someone is a member is always a bad idea. It solidifies their membership and turns them against you.
The recipient of these messages had a new identity now that is largely derived from the group. Every attack on the group becomes an attack on him. He would sooner disassociate himself from me than the group.
If you want someone out of a bad group, don't criticise their existing group, invite them to join a better, tighter, more-fun, group.
Likewise, you can’t get members to leave an existing community by criticising the community. You're just going to turn all members of that community against you. You have to invite them to join a tighter, more exciting, community.