It's the world man, dumbasses run freely with no remorse!
Second'd, even though I'm lucky enough not to have a mental disorder(For lack of a better word) it's rare to see people use that as a reason to act like a dumbass.
For example, I have a friend who's dad is a crazy alcoholic, parents split and he's been kicked out of both houses simultaneously, and has bi-polar disorder/ADD, NEVER uses any of that as an excuse.