Why are ppl so depressed?

Why are ppl so depressed?
Ok, I know that everyone must have been depressed some time in their life or will be. But if you've been depressed for a long time, why?
Why do you hate the world?
I know that people will tell you (mostly counselors who don't know a thing of the world) that you will meet better people soon. But I know from experience that sometimes they are lying. No one was there for me when I needed them the most, though when they needed someone, they would come crying to me and I would take care of them. Those are not real friends. REal friends are there for YOU when you need them also, so the seesaw wouldn't be down on one side. but unfortunatly, the world isn't like that.
Why do people get so sad for such a long time? If someone very close to you died, I can understand why, but if not, then why are you sad? Don't gather up all the thorns in the garden, or grieve on how imperfect your life is, but instead, try to look for the pretty flowers in the garden, or try to look at the good things in life. If there are no pretty flowers anywhere, plant some. Start over. Apologize to the people that you regretfullly hurt, and try to get along with your family. I know that it's hard (especially if your family is difficult) but try anyway.