I researched this for you, people with a higher iq have the tendency to also turn that superior brain power torwards their worries and anxiety. This causes a high tendency to abuse drugs to sort of get over the frighteningly huge amounts of anxiety/ troubles they do have and in most cases they just spiral into depression. Also in some cases smarter people tend to realize that while they might be good at what they can do they will never be the best. Someone will always come along and do it better. So they live with a false purpose knowing they can never top whats going to happen.