I wouldn't apply this to life in general, and I feel that my friendships are very important, but as far as uni is concerned I do tend to take this approach. I have made friends at uni, friends I really like and keep on my social media and chat with from time to time, but I have no intention of going out with them, attending social events or anything of the sort. Especially not during the academic year.
This could just be because I'm quite socially anxious, I don't like to drink or dance and parties or social gatherings make me generally uncomfortable, but I do make the effort to see my life-long friends (friends I have had since I was a child) every other week, or every few weeks, because I want to maintain these people in my life.
Friendship is great and I will often talk to my uni friends about work, the course and exchange ideas about our essays and chat whenever I see them in lectures. It's nice to have a group to work with and sit next to. However, I'm paying £9,000 a year to get my degree in the end and if I wanted to treat having a good time with friends as more important and ruin all my grades, I need not have bothered going to uni in the first place. I'm content with my life, it is full and busy with my spending a lot of time with family, my boyfriend and his family and the rest of my time going towards personal time and friend time. When the academic year starts, friends take a backseat and personal time becomes work time. That's just how I like to live my life right now in order to stay calm over all the work I have to do and it works for me.
However, that's not to say others should be the same. Some many people attend uni for the uni experience, the dating/sex/drinking/clubbing/nightlife or just wanting to find some life-long friends. That's totally fine, you're paying for it after all and if that's what you want out of the experience it'll be all worth it hopefully.