I despise vigilantes. Usually they are getting just as much of a perverted kick out of harming the alleged perpetrator. In fact I think that's often why they do it; to try to find a socially acceptable way of enacting sadistic fantasies, especially when it comes to harming weaker people. Because this is a kind of perversion and because otherwise they'd probably do it to one of their own family, they particular target sex offenders because they consider that those people have also preyed on weaker people, so attacking them means they see themselves in the alleged sex offender (which makes them angry/in denial), but by joining a vigilante group they can externalise their own similar urges while still remaining socially acceptable/justifying their violence to themselves.
Also a lot of what they do is entrapment of people with learning disabilities, autism, etc. For example, I saw a video of some of them pinning down a young man who was clearly intellectually disabled, and they kept asking him why he replied to their messages where they pretended to be a teenage girl. Now I'm not saying this man should have replied, but he was very unlikely to be fully aware of what he was doing and probably never had any girl show any interest in him before. So he was an easy target to set up, even though he hadn't actually abused anyone. It didn't seem to matter to the vigilantes that he was clearly not understanding why they were attacking him; in fact they seemed to enjoy it more because he was weaker. The police need to do more to stop this as well as tackle sexual offences better.
I can understand it more if someone has done something to you personally or a member of your family and you feel no one is doing anything about it and justice hasn't been served, but as far as I can see that isn't the motivation of most vigilante groups, especially because there often isn't a real victim involved and they've set someone up online.
