You know this. Yet you're asking why they won't do it. You can't force someone into a particular occupation.
WE enable that behavior.
If a person if faced with the proposition of work or going hungry and not having a place to sleep, they will pick work, even if that job isn't necessarily what they want to do or will do for the rest of their lives. It is work. It's why I work, and I've done plenty of work I felt was beneath me, and took the attitude that I would determine in myself to be the best I could at it with the hopes that I would get a better job, and I did, and so on.
However, when you don't require a person to just get to first base, nay, swing the bat, then I guarantee you they will never progress.