Now that finals seasons is over for this academic year, it's easy to look back and evaluate the sources of stress. I know that graduate school can be disproportionately stressful, whether it's a Masters' or PhD program. And I was just thinking of potential reasons why that might be.
One of these reasons is probably because there is more skin in the game. For some, that might mean that their academic performance is more closely tied to career success, hence the pressure to do well. Masters' programs are often directly associated with a more explicit career path than undergraduate programs.
Secondly, there's just more responsibilities, the older the adult you are. Especially if they're a PhD candidate, who are often burdened by having to balance qualification exams, research, and teaching in addition to adult responsibilities someone of their age would already have (family, home, car, etc.).
Another reason might be due to the prevailing capitalistic credentialist credo that says it's never a bad decision to get more degrees (but it oftentimes is). When college-educated folks don't know what they want to do, they tend to go to graduate school, find out that it isn't what they want to do, then miserably stick it out (due to sunk-cost fallacy) or drop out while tens of thousands of dollars in debt. (On the other hand, I understand that there's a prevalent narrative tells us that we can drop out of school and teach ourselves skills to become rich, but that's survivorship bias.)