To the girl who thinks it's cool to be mean to other girls just to make yourself feel better, take a look at what you're doing. I've never understood what the thrill in tearing someone down to make yourself feel better is. How does that make you feel powerful?
How does being mean to others make you feel like a good person?
I'll never understand why you think it's fun to be mean to your own friends. When your best friend runs to you saying that cute guy across the bar finally noticed her or that she had a great day, why is your first reaction to say "he's not interested in you" or "yeah well my day was better."
It takes way less energy to be happy for people than to go out of your way to put them down. Seeing joy in others should make you happy, not feel like you have to compete with them. Happiness is not a competition in life. Everyone has their ups and downs, that's just how life works. Take that into consideration next time you want to make someone feel bad for being happy.
From someone you've constantly put down to make yourself feel better, I feel bad for you. I'm sorry that someone has made you feel like you have to be superior to everyone just to achieve happiness. I'm sorry you don't know how to be happy for your friends happiness, but maybe you should give it a shot.
And from all of your "friends" you've been constantly putting down, eventually you won't be a friend at all. No one needs a friend that is always making them feel bad about themselves. Whether it's saying they aren't good enough or pretty enough or whatever it may be, no one needs a friend like that.
So, I challenge you to change your ways. I challenge you to see the good in other people and be happy when they are happy. Learn to be encouraging and have a kind heart and to be nice to your friends and the people who have stuck around this long. If you continue to put others down in order to make yourself feel better, I promise they aren't going to stick around to let you tear them down.