Depression is caused by a shitty life. Most people with depression are trapped in an abusive relationship, though often it is with themselves. They're trapped by fear of admitting failure and making changes.
a lot of times its a abusive mindstate.... a lot of really really down bad people have went on to do great things. its all about your perspective
Absolutely. The best parts of modern psychology are CBT and finding a better mind state. The drugs sometimes help shake up your mind enough to find that.