When I was in grad school, 100 hour weeks and working 100 days straight was the norm. Also I made 25k a year. And I loved it, because I loved doing science and I got to be paid to do what I loved. And also, it's maybe worth mentioning that your experiments don't give a damn about labor laws. There really are some important societally beneficial things that simply won't get done if there aren't crazy fuckers like me around (not necessarily the projects I happened to work on, they all turned out to be crap)
Honestly what made me mad was that there were a lot of kids who got out of college, and went to grad school because they didn't know what to do next and nobody told them how crazy grad school was. These jokers depressed the asking price for a grad school salary.
Because you're normalizing abusive workplace practices. Need I explain further? It's not right, it's not okay, and if you tolerate it, you do a disservice to your colleagues. Maybe you don't care, that's fine. But when you say "What's wrong?" I will point out that it is not to be commended or supported.
If your employer encourages, supports, or allows this sort of behavior to exist, I hope you find yourself on the business end of a lawsuit.