I guess other people have more nuanced theories, but my simple answer was that people prioritize different things. I'm not sure "there aren't that many poor NBA players anymore" is the answer, nor am I convinced that a lot of them don't already have tattoos coming into school.
Of course, the word poor has a different meaning depending on who you ask. I don't think anyone is under the impression that these guys are homeless or hungry (though some are) and if you look at a guy like Shabazz I'd say it's easy to misconstrue his point. However you define poor or however many boneyarders grew up in the real world where there were consequences to mishandling money, the point is that it's OK to make life easier on college athletes who generate billions of dollars.
Edit: not trying to come off as antagonistic since the OP poses a legitimate question. I just see how it would be easy to draw the wrong conclusions from this premise.