My brother is 31 and like this. He’s severely mentally ill.
We think he also has Pathological Demand Avoidance - he can’t even cope with his own internal demands like cleaning his teeth, eating etc.
He can’t cope with the mental demand of anything physical including hobbies, so he just paces up and down all day daydreaming. He daydreams about his ideal life where he can be normal and productive. No video games. He does faff on his phone or youtube for hours a day.
He eats uncooked food out of packets (eg crisps) and a meal when he can mentally cope with my mum cooking for him. He eats the same strange meal over and over again (pasta, hummus, and mixed frozen vegetables). He does take supplements to compensate.
His house is still hoarded from when our dad died a few years ago. He can’t cope with cleaning or maintenance.
He can’t cope with basic life admin and needed a lot of help to go on benefits after our dad died. (He had been living off the benefits of my dad - also mentally ill - and another elderly relative. In exchange my brother was their mental support as they had severe autophobia, so they were delighted for my brother to never go out).
He left school in year 9 and has no qualifications or work experience.
He doesn’t socialise as he has strange and unreasonable beliefs about people, and fixates on things you don’t have in common, instead of what you do have in common.
He’s extremely depressed and has no confidence.
He is polite to outsiders on the rare occasions he sees them, but rude to me and my mum and we never know what is going to upset him. He often perceives basic suggestions or questions as unbearable demands, but not always, and there’s no consistency in what triggers him. He is paranoid and always thinks the worst of people’s intentions and thinks we are deliberately triggering him for fun.
He says the pathological demand avoidance feels like his brain shuts down from intense stress and he literally can’t do things, not that he merely doesn’t want to.
The more he stays inside, the less capable he becomes.
I do think this is becoming more common due to the hopeless society we are living in. I also suspect pollutants etc are building up and affecting our brains in ways we don’t yet understand. Finally I think video games, computers and smart phones are rotting people’s brains, and these have only been around for a couple of decades.
But we do need to remember that until recent history, people this mentally ill would have just perished. In advanced societies we can support them.