We didn't evolve to be rational, we evolved to survive. "Personality disorder" implies that there's something wrong with the individual, which I don't particularly agree with.
"Eat as much food as possible" and "hoard useful resources" have been successful evolutionary strategies for pretty much the entire history of life on earth. Abundance is very, very new. No species can fully adapt to a completely different ecosystem in a few generations. Most of us have at least some maladaptive responses to abundance. Some people eat too much, some people own too much stuff, some people drink too much alcohol, some people are scared or sad all the time for no obvious reason, some people lose their life savings to imaginary internet money, some people spend an unreasonable amount of time playing Candy Crush or reading Hacker News. We're just not built for the modern world.
I'm not endorsing hoarding as a lifestyle. I'm not saying that it's healthy or rational. I'm not saying that we should leave hoarders to their own devices. I'm saying that it's not crazy, just an obsolete strategy. Looking through that lens gives hoarders a means of understanding their behaviour and gives us a means of helping them.
Hoarding useful resources is an important instinct. When the instinct is so strong it causes serious problems, and the person is unable to control the instinct with his will and intellect, or is unwilling to try, then it's a disorder.
Your evolutionary justification is cute, but you're ignoring a lot of counterevidence. For example, in what conceivable evolutionary tale is it adaptive to be surrounded by vermin, feces, and rotting garbage?
"Eat as much food as possible" and "hoard useful resources" have been successful evolutionary strategies for pretty much the entire history of life on earth. Abundance is very, very new. No species can fully adapt to a completely different ecosystem in a few generations. Most of us have at least some maladaptive responses to abundance. Some people eat too much, some people own too much stuff, some people drink too much alcohol, some people are scared or sad all the time for no obvious reason, some people lose their life savings to imaginary internet money, some people spend an unreasonable amount of time playing Candy Crush or reading Hacker News. We're just not built for the modern world.
I'm not endorsing hoarding as a lifestyle. I'm not saying that it's healthy or rational. I'm not saying that we should leave hoarders to their own devices. I'm saying that it's not crazy, just an obsolete strategy. Looking through that lens gives hoarders a means of understanding their behaviour and gives us a means of helping them.