I'm sure many do. Working hard is a privilege. Society has to put a lot of trust in you for you to get the opportunity to work quite hard. Society has to expect something out of you. And for you to be willing to put up with that, it's probably something you feel a deep connection to. So while I do believe that everyone should be working reasonable hours for a living wage, I'm not going to pretend that PhD candidates aren't still in a privileged position. There are people wasting away on disability or their parents' dime or flipping burgers who would love to get the support necessary to work very hard at an interesting problem.