There's no "age limit" for enjoy something. Id you like it, you like it; it's that simple.
I'm too old for games? I am too old to still care with others peoples opinions.
Yup. If someone is really curious or if it's someone like a friend or family member, I usually simply state that the age demographics are actually largely made up of people ~16+. I'm sure we've all seen the picture where it shows COD and Pokemon, and says the targeted age group for COD are adult men, and Pokemon for younger audiences. Then says how it's really flip-flopped.
Besides, if they doubt you just show them the equations for things like IVs and catch rates. They'll be too intimidated to try contradicting you lol.