There are hobbies for sure, but when you spend 80,000 Hours in a career which you feel helps no one but you with your income, you might find mid-life there are more-important things.
https://www.effectivealtruism.org/ & https://80000hours.org/
You say "why won't people help in San Francisco". This betrays a severe misunderstanding of effectiveness. How many thousands of dollars would a single individual need to give to a charity working in SF to help one person as much as they can with a $2 donation to AMF (Against Malaria Foundation - providing protection from malaria for 3 years). People are people, regardless of where they were born, and helping more people is better than helping fewer.
"Most people will see [this activity] as very out of touch". So what? Most people saw gay rights as out of touch, most people still see animal welfare / animal rights activities as "out of touch".
The following video by Peter Singer is a good intro to Effective Altruism and the philosophy behind it. His essay "Famine, Affluence, and Morality" was one of the primary influences on the founders of the movement.
https://www.youtube.com/watch?v=Diuv3XZQXyc
It's true that more recently many people in the movement have shifted their focus from global health and development to areas like AI risk and biosecurity. Whether or not you agree with working on these areas, I don't think the people working on them are doing it cynically. I think they are motivated to work on these areas because they believe it will do the most good for humanity.
I don't have any experience with the actual culture of EA, but the concept and the philanthropy itself seems at least as good as other charities or mission-focused organizations.
Like spending £15M for real estate [0].
As selfish as it sounds, saving (an expected) 186.328 lives in Africa will not create the "feel-good chemicals" that teaching a kid to ride a bike will.
Rationally, it's a good thing. But emotionally, I don't think it's actually all that effective.
As a result, I changed my career path (slightly! not even a whole blow-up-your-life thing) a year ago and have been happier since.
I also really liked the book Four Thousand Weeks, which is all about figuring out how you want to spend your finite lifetime.