[sidereal1]

It's not just about money. Someone who is severely mentally ill isn't going to able to perform tasks, let alone function without a caregiver.

Living on the streets is very dangerous and stressful. Somewhere around 25% of homeless people have traumatic brain injuries. Not the sort of people you can put in a cubical to do data entry.

[ethanbond]

Mental illness is a huge component to this, I agree. I think it's pessimistic to say that a sizable portion of this group couldn't become employed in some way. First, not all of them are mentally ill to begin with. Second, a lot of mental illnesses are quite manageable with the right care. Care requires money, and money is acquired by working.

Further, no mental illness has ever been alleviated through boredom, malnutrition, lack of sleep, social exile, and maltreatment.

Also, not every job involves sitting at a computer ;)