[JamesianP]

I don't see where you get any of these assumptions. If anything I'd say a phd is disproportionately attractive to poor students precisely because it pays living expenses, unlike many popular professional degrees which are much more daunting financially (i.e. medicine).

And students literally are killing themselves at universities because of how well they are "set up by their parents" to succeed. This whole line of thinking seems extremely naive when it comes to what people have to sacrifice to succeed in any pursuit in life. Personally I'd say the single most important thing needed to be happy in grad school is friends and a social life. Like everywhere else in life. Liking what you do comes in second.