How Do People Attend Concerts Alone?

I rushed home as soon as I received an email letting me know that my profile was accepted (I'm sorry but I was excited). Rewind it back? I decided to go to a concert alone ---- Now in my late 20's friends outgrow eachother or are entering the family phase. I looked around and everyone had big groups of friends like I once had--- don't get me wrong they're still there, but it's just different. As I akwardly held my drink and took sips of it every 5 seconds it hit me --- I'm not as confident being there alone like other activities. There's something about being the lone wolf concert goer that didn't sit well with me. How do people do this?