I suspect it's due to a happy lifestyle. I don't "suffer" from it in my own words. I'm happy and very solitary. It's how I've always been (being the smartest, fearless, capable and most interesting person I know). Now, being that the concept of friendship having different levels of intimacy, you can do the math (see Proverbs 18:24 via Luke Cage S01E09). At a certain point, your learn to shed unreliable friends and real friends die off or move away or change...suffice to say it's rare that you're going to follow alongside their life path when you have means. I've been perfectly satisfied with my life about 8 times and most of those were when I was alone. I will probably die very much alone and as close to perfectly happy as I can manage. I just don't see it as a problem, but as a coping mechanism for lower income communities. It's probably true that I could be happy with other people, but I just can't stand most of them outside of work (I can limit relationships to working toward a common goal).