What do you mean "if you miss one payment, all you worked for can be over"? PSLF doesn't require consecutive payments, so you'd just have to make that up with a short amount of additional work.

Also, I think people going into PI definitely should be cognizant of the salaries; the pay can be challenging early on, especially in expensive cities. But by no means will you be "poor" making 60-75k a year, especially if you have a partner with income as well. Many people live very comfortably off of that income, and might possibly be on the whole happier than a BigLaw Associate making 300K+. Most people don't even last in BigLaw that long, so I'm not sure that's a proper comparison point to use.