There is no such thing as a libertarian mob; we'd rather just take a nap or read a book. I think the people most afflicted with group think are people with self-confidence problems; this manifests itself as a disgusting need for approval in others. Every nut in Antifa/BLM/KKK, etc. is a weak-minded person who wants to be led around on a leash and have others think for them; this isn't a problem except that the leaders are similarly very flawed people - usually drug-addicted celebrities or slimey lawyer turned politicians.
That might be true, it also may be false. I think its difficult to generalise. People do the exact same thing and have very different motivations.
Its where that saying about doing the right thing for the wrong reasons comes from (although more often I see people doing the wrong thing for the right reasons, its just a bad, maybe worse).
Although, what you're talking about, its been studied and discussed before now, Karen Horney called it the "neurotic need for affection" but she didnt use words like "weakness", which are pretty loaded terms, instead she talked about "basic anxiety" and thought it began in the family home, attachment style and/or deficiencies or disorders could be something to do with it.
I might describe it as a "character flaw" but I know that's a loaded term too. I would say that as I personally prefer some of Erich Fromm's ideas, he thought there was a drive to freedom, which every person experiences and is as powerful as any other drive, maybe more so, but social context, circumstances, some as simple as wanting to be a success, mean that people forfeit their freedom, repress it, adopt a "social character", which is determined by a "social unconscious", and do their best to conform to that. There's the main culturally patterned "social character" but there's subcultures or "scenes" etc. which have their own, its usually a variation on a theme.
Fromm identified a bunch of what he thought were unhealthy types, he had his own typology or characterology, but he thought this changes all the time too. Like he didnt try to develop any kind of a theory which was ahistorical or anything like that.
Anyway, I think character is an important idea, less thought about or talked about these days but it used to be really important, in a broader sense than mere integrity. Even if you think its a fiction agreed upon or social construct I still think it matters and so its how I'd look at things like this. Also Fromm would have suggested that boredom has a lot to do with movements like that. I'm inclined to agree with that. Its not merely boredom in the sense of being unoccupied, its a little bit more compelling than that, because I think you'd have to be pretty damn bored to seek out the kind of trouble that most of these groups generate or attract.