I prefer: Dogs are pack animals. Horses are herd animals, therefore we are horses. (I always wanted to be a horse, not just ride one!) 
I think we grow and change more by interacting with others rather than being alone. Being alone has the advantages of never having put the needs of others above your own, never having to take criticism, and never having to think there may be a better way of doing things than the way you are comfortable. When you’re alone you are your own echo chamber and hugbox, and nobody is around to shit in your punchbowl about things that make you happy.
But when you interact with people, you gain a lot of feedback about yourself. You get a better sense of your strengths and weaknesses. Being alone does not give you the benefit of this pushback. Maybe the guy the OP was talking to decided sitting at home alone playing video games all day wasn’t fulfilling enough, he wanted to interact with living human beings and socialize. I know one of my regrets is not making any lasting friendships in college, but this was my own fault because I wasn’t willing to be proactive enough to seek out and build these kinds of relationships.
People grow up. They learn in hindsight that what they thought they wanted/liked is no longer what they want or like. They look back and regret the choices they let pass them by, the opportunities they didn’t take. Sitting home alone watching My Little Pony doesn’t help.
Well at least we are not lemmings:
