There's no cut off. Some people are just judgy (and often hypocritical).
I'm the same age as you and I've been gaming my whole life. My father had all the Ataris, (2600, 400, 800, XT, etc...). He and I built my first 386 together. My uncles had the Intellivision. Cousins with the ColecoVision. My father's almost 70 and he's still an avid Destiny 2 player.
I will admit tho, it's harder to find women, our age, who are either into or at least open to gaming as an adult hobby. I'm not saying they don't exist but having been divorced and remarried I can say there's a gender gap there. I was lucky enough to find someone open minded. She never complained about my weekly game nights to keep in touch with my friends and she's even opened up over the last few years and has become a bit of a gamer herself.
So... there is no cut off. It's not immature or childish, and it's certainly more of an art form than 3/4 of the garbage those same people will spend their free time on (reality tv, tiktock, endlessly scrolling the void of facebook).
That's also asshole design. Most people are behind some form of nat. It's especially egregious for customers of ISPs who use CGNAT.