Working on yourself is a more-than-full-time job, and it can take years of work for someone who's developed so much self-loathing. Hobbies are for people who aren't constantly busy with other obligations. And if you're working in solitude in software full-time, you're going to have a hard time finding a hobby that you can just get laser-focused on, not to mention time for exercise if your hobby isn't athletic.
The isolation is because we're an atomized society. Humans are psychologically supposed to exist in stable tribes. These have been shrunk down to nuclear families in modern life.
You're just making a lot of assumptions that conveniently allow you to dismiss and deny the reality of the situation.
I realize there's a problem. I also realize nothing I can say will solve that problem. It's up to tenonyx to solve it. I'm not trying to solve, just trying to help show a perspective on it that one might not immediately see. Because I've been there, too.
However, I do agree that you need to get past self-loathing to at least self-acceptance of some kind. Mostly because self-loathing means putting your attention on yourself, and that is what makes it hard to connect with other people.
It’s ok to not have a high opinion of yourself as long as you don’t place too much importance on it, and are on with yourself.
You have you not actively dislike yourself.
Simply "chosing" to be happy is like simply "chosing" to be a milioniare.
Also, my impression of NYC, more so than any other place I've lived, is that there is a general rejection of the idea that your lifestyle is supposed to change when you're 30.