Indeed. I've known a lot of unusual people in my life, and while I form opinions about how they think and react, I think of those opinions as just getting to know someone's personality. I'm always fairly startled when someone refers to the personality of someone I know using a medical term - although, in some cases, they're correct, I can't help but thinking most cases "oh, the medical community has so trivialized that definition that it now applies to people whose problems aren't even serious. As well as those whose problems are."
Besides, a lot of those traits, while their bearers are unhappy people, are important to the proper functioning of a group. You need a depressive around to temper the stupid optimism of most normals. You need a few manic optimists and adrenaline junkies to explore and make new discoveries for your people, even if a bunch of them do get killed in the process. You need obsessives if anything important is ever going to get done. You need an insomniac if someone is going to warn you when something is threatening your group at night. You need the maladapted, to lead the way when it's necessary to adapt to a new situation. You need a paranoid to warn you when someone really is out to get you - normal people never notice until it's too late. You even need people who don't go into hysterics at a disaster if you're going to have an immediate and appropriate response.
It's the mix of different people that survives. If everybody were normal, the group would have too limited a range of responses and would fall into a sterile routine where nothing new ever happens, no new discoveries are made, no one has a clue how to adapt to anything new, and while most disasters would get a correct response, the group would be wiped out by the first few that they just don't have the right person to deal with.
So, yeah. There are a bunch of personality types that have unhappy lives most of the time. The current fad is to try to medicate them out of existence. But the traits that are problems for them personally, are often traits that society as a whole needs a few people to have.