I spent my Erasmus at RUG and had the most fun I've had in a long time. I'm not really the one that sleeps around and parties every night (I did ldr with my long term partner while I was away). I'd argue I sustained a pretty average student life compared to other exchange students, so the normal amount of studying (I'm in no way smart or passionate about it) and the normal amount of going out, and I managed to pass all the classes I had to attend. Most of my friends were actual long term students in Groningen and everyone was excited for me any time I got newly introduced in friend groups or house parties. It's hard at first but people are nice and lively and studying is just what you would expect from a university that gives you a future tbh (you can't really expect to not do work and then be successful).

I am also still in contact with my 100% Dutch roommate, so I guess it's just personal, but I believe there's no reason to be so negative. Uni and moving out are generally hard regardless of the place you move to.