I could not wait to end university, so that I can stop using big tech products. Unfortunately people only use products they are familiar with. If they are always on facebook, they use that for groups. Good luck finding a local community uses anything but facebook groups.
Edit: at university, many pieces of info reaches you informally. If you are not talking to classmates, you might miss important news as well.
I mostly agree with you and frankly it is enough to have one friend who uploads their contacts to big tech firms with yours included and maybe tags you here and there and you are already uploading data without your consent.
Although what I see recently is that facebook fails to recommend anything interesting to me. I had to keep my account, but deleted everything from the day of my registration and haven’t uploaded a single thing for years.
My wife sends me products she finds interesting and they all contain the facebook tracker at the end. It is a scientific fact that women are better consumers, hence ads are mostly created for them. My wife hates ads while watching videos, but taps on them during scrolling all the time. Fortunately I haven’t been asked to get her off pi-hole. It is tricky with ads, as you think that they are offering a solution for something, but in many cases they are establishing a desire you did not have before.
That explains it, then. Here it costs around 11 US cents per message. So if you are messaging a lot, they will add up at the end of the billing period.