I'll be 20 in a couple months. When I was twelve I quit playing the TCG, I "grew out of it". Last year I decided to start playing again because all of the reasons I quit as a kid didn't matter anymore and I missed how much fun it was. My girlfriend who had collected in her early teens but never played got into it with me too. It's something we both get to spend time together doing. We made a close friend through league, he's 38, he works at a bank and has a nice house and a son and he loves playing Pokemon. When I started playing again there was one person I didn't want to tell, one of my best friends I grew up with. But when I had a picture of me in the newspaper at a tournament he found out and told me he thought it was pretty cool. He even wants to come to a tournament some time to check it out.
So no, you are not too old.
So no, you are not too old.