Only because people thought the comic was going to be worth something one day. But it was just a mass produced cash cow.
It's only worth like 15 bucks now.
It's ironic in that if a lot of people think a largely available collectable, in comics or pretty much any other type of collectable, is going to be worth a lot of money it's almost never going to be the case for just that reason.
It's also just another reason people should collect things because they like them and not because they think they will make a lot of money in the future. I know I enjoy having my comics now just as much if they are worth ten cents or fifty dollars. I don't even know what any of them are worth and it doesn't really matter to me that much.