What are those numbers as a percentage of users? I suspect there will be fewer cocaine users, because it's illegal. Also, people may not admit to using it as readily, because it's illegal.
I have never knowingly known anyone who takes it. I am not naive enough to think that means no one I've ever known hasn't taken it at some point - I'm sure they have, I just don't know. The girls who were popping pills in my house-sharing days probably did coke too. A former colleague who died of a heart attack in his early 50s I suspect was a user. And certain other colleagues who had tendencies to be utter arseholes and known for big nights out, i am fairly sure they used. But I don't know for sure about anyone.
I'm not that keen on alcohol either, for many reasons, including having had an alcoholic mother. But it's legal, which means it's socially acceptable for most people.
I probably wouldn't choose to be close friends with someone I knew was a user, but as I say, I probably do have friends I just don't know about.
It's not compulsory to be friends with anyone. It might be difficult in some cases if you choose to drop someone, you might lose that whole social circle. But it's a choice you can make, and if it's a line you don't want to cross (or sniff), that's fine. You don't need others to decide for you.