I'm not going to take a friend to a concert anymore
What is your reason for deciding to no longer take them to the concert?
I don't like that friend anymore and their life choices also bother me.
I can understand being annoyed with a friend whose behavior you don't like. But if you have already made plans to go to a concert with your friend, you should consider following through. It is rude to abandon plans you have made with people.
It doesn't matter if anyone knows about it. I want to ignore.
Backing out of previous plans that you have made is pretty messed up. If you are no longer friends with them however it is your right to do so as long as they didn't spend money on the tickets. This is really your own decision as the context really matters big time.