incels
There are personality traits that made even angry 20-something-me different, but I honestly think the BIG difference between now and then is internet based.
There's a very human drive to feel supported and heard out in a group, so all you need is a group which supports the worst indoctrination to get someone turning that anger outwards rather than inwards.
And all you need to get *that* group going are a small number of people who honestly think that direction and love the attention.