I think sometimes my friends hang out with me because I make them feel less insecure about their looks
What makes you think that?
For instance when we go to the pub and they buy me a lot of drinks like they like to make me feel happy
You're probably just overthinking things. Your friends likely just enjoy spending time with you and there's no ulterior motives.
But I read this article once that described people like that, and my friends act like that to the letter!
I still think you are overthinking things. It's good that they want to hang out with you. Don't ruin that with wild speculation.