For me college was the most stressful. High school was a breeze then all the small anxieties I had in high school just got amplified in university. A lot of it was fear of failure. In highschool you get a bad grade it goes in your nebulous "permanent record"

I went to an expensive out of state school and it just felt like the stakes were so much higher. A bad exam could lead to a low GPA, loss of scholarship, being pushed out a program or major, academic probation, etc.

In the working world I met so many successful people who failed at some point, have a criminal record, poor credit scores, bad employment records, etc. and it never seems to go as bad as it's portrayed.

Even creditors don't scare me anymore. I just tell em to fuck off, verify the debt, and never contact me by phone ever again. A younger me would freak out about my credit score if a collector called. Because I thought that's what mature adults worry about.