Throughout my life, I've befriended several people like that. They all have mental or physical disabilities, but you would never know until they told you.

other people pay your bills for you. and give you spending money

I'd assume an extreme situation of executive dysfunction combined with some amount of mental illness. Anon's parents are most likely middle class and don't want him to be homeless, and may have not engaged enough with him as a kid/teen and left him to his own devices too much leaving him socially and emotionally stunted compared to his peers.

It's really a challenge that compounds on itself. You feel stunted compared to your peers, so you interact with them less thereby getting less chances to build those social-emotional skills. You pull in more and spend your time isolated and slowly your views of the world get warped by whatever media you consume instead of spending time touching grass and talking to real people in the real world. This then makes it harder to get a job which then makes it harder to go out into the real world to course-correct. As you get older it becomes a bigger and bigger red flag that you've never worked or lived independently, so people are less likely to connect with you. You become more weird and off-putting, and it's just a death spiral that ends with a sink or swim situation of some sort unless the individual happens to connect with someone with the patience to help them build those social-emotional skills they missed out on years before (most commonly a romantic partner or a real life friend)

People are so much more rude when they can’t see your face!

Unsolicited sales calls - especially at modern day volumes - are about as well-received as someone knocking on your toilet stall to try and convert you to Jesus.

Getting a call center job to overcome your fear of phones sounds like getting waterboarded to overcome your fear of drowning.

I think people who do work that involves contact with the general public have to be petty emotionally resilient. I am no good at it. A lot of the public are utter wankers and throw you into fight or flight mode.

It’s not just rude, it makes you look dumb as well. People can have different experiences and views to yours without it being a symptom of mental illness.

You'd be projecting a lot onto my simple statement. Not everything is about you and your personal issues.

Edit: Just saw this was a tankie so this checks out.