I'm in my 20s and the way a significant portion of relationships start in this generation is via dating apps. If you aren't using dating apps, and don't have social circles, there's just no social fabric to build from. Believe me, I've tried activities, they don't really work. It's extremely difficult to build enough rapport with someone in the space of 1-2 hours that they'll care enough to ever meet up again.
So change careers, change city, change country, change whatever is needed so that you can have a decent life.
I actually go out a lot, and moved across the world to Tokyo four months ago. The problem is not meeting people. I can make surface level connections every day of the week. The problem is finding people who want to stick around.