Matt Damon claims true friends are extremely "rare".
The 43-year-old has made a name for himself in Hollywood thanks to starring roles in films such as Good Will Hunting and the Bourne franchise.
Over time he's realised that there aren't many genuine people around and that he needs to be wary of those simply wanting to get close to a celebrity.
"You have no idea how rare true friendships are," he admitted to the German edition of OK! magazine.
"Of course people are saying nice stuff to me every day in order to start a conversation. But that doesn't really have a lot to do with true friendship.
"With time you do start to develop a real sense for realising when someone is really interested in you or when they just want to know you because you're famous."
Luckily Damon does have a good friend in fellow A-lister Ben Affleck.
They have been close since childhood and as they both struggle with the pitfalls of fame, their bond has only intensified.
"He knows a lot about me. Years ago, when I told him about the most personal dreams I had as a small boy, he didn't laugh at me, nor did he tell anyone else," Damon smiled about Affleck.
Damon is married to Luciana Bozan Barroso and the pair manage to raise their four children in a normal manner.
In contrast, his famous friend Brad Pitt, who has six children with fiancee Angelina Jolie, isn't so lucky.
"If you can control the celebrity side of celebrity, then it's worth it. I look at Brad - and I have for years - and when I'm with him I see the intensity of that other side of it. And the paparazzi and the insane level of aggression they have and their willingness to break the law and invade his space - well, I wonder about that trade," he previously told Esquire magazine.
"I remember telling him that I walk my kids to school, and his face just fell. He was very kind, but he was like, 'You b*****d.' Because he should be able to do that, too. And he can't."
