Trans ideology encourages children to chase the lie that they can change sex - which will become more obviously a lie at puberty and as they age. It tells them that normal interaction, correct sex pronouns used unconsciously or someone recognising their sex is 'hateful', that it means whoever recognises their sex and shows it 'hates them' and this is 'trans genocide' and they should 'fight back'.
Not bowing down to their every demand is 'hatred'. They are the main character, everyone else is a NPC and disposable. It's really, really abusive to encourage this sort of mental disfunction in kids. It's encouraging extreme narcissism and lack of resilience. 'Social transition' and 'affirmation only' is frankly evil and does not result in mentally healthy young people.
The Lt Govenor of Minnesota wore a 'protect trans kids' t-shirt with a knife on it, and this sort of violent imagery is far from rare.
What a surprise (not) that some of them will end up doing this. Maybe most particularly when they realise their 'trans' identity is a lie as this killer seems to have, but that there's really no way out. It's really interesting how the cultists (e.g. the BBC) still stick to wrong-sex pronouns rather than reality based pronouns. Apparently it's self-ID until it's not within the cult's rules, and then it's not. This male killer said he was fed up of being trans after all.