It's funny, I spent years helping a former friend through his depression and isolation, and was always there for him even when he left school and had no one. Years later, he managed to improve dramatically, and became very popular, forming his own group of friends who followed him loyally. I was never a blind follower though, just a friend who treated him equally.
As I got older, some bad events had built up until I became depressed and suicidal. The best friend who I'd helped for so long decided to exploit my depression, used me for my money (which was spent on drugs) and basically treated me like crap (his followers did too). In the end he only cared about money, all that I'd done for him meant nothing. I was cheated and lied to by the group of childhood friends I'd trusted for so long. Betrayal hurts.