What happens to autistic people when they grow up?

Depends on their abilities. There's not one path for every person. There's an old saying that if you've met one autistic person, you've met one autistic person. They're all so different. Some will go to college, get jobs and lead pretty "normal" lives. Some will need assistance in some areas of their lives. Some will need assistance in every aspect of their lives.

Depends on their capabilities.

I go to college and study a proper academic course - psychology, criminology and sociology - and I am capable of living by myself (although. I actually live with my mum). I can manage my own finances and I can also take care of myself. Next year, I am off to university to study law.

My uncle lives by himself AND runs his own business. He has always been independent - even when he was married.

My cousin, on the other hand, is severely disabled by his autism. He cannot live by himself, he has little concept of danger (will run into traffic, so someone always needs to hold his hand), cannot even do basic cookery, has the language skills of a two year old, cannot read or write, not does he understand money. He has full time carers, and at the age of 26, he will never be independent or go to college.

You never see a grey haired one

They become decent intelligent adults in society.

Depends on the kind of autism....