Having autism sucks massively. If you try to join autism groups, the majority of members are often extremely high functioning, borderline Albert Einstein kin savants who scoff at anyone who doesn't consider autism to be a gift that's been packaged alongside some unnecessary add ons.
If you don't fall in line with that sort of personality, the flavour of autism that defines itself as "too weird for normies and too normie for absolute weirdos" there's such a chasm of relatbility and the lack of belonging anywhere hits you like a ton of bricks.