When I was a kid, someone called me a nerd for reading comic books and I stopped reading comic books, what mistake did I make?

The mistake you made was listening to those morons.

Comic books and graphic novels are wonderful.

you shouldnt listen or take so serious what other people said to you . when someone called you a nerd doesnt make you to stop reading comic books. i was a nerd girl and no body called me a nerd when i was reading a comic books . reading books and comic books doesnt make you to be a nerd  or geek. make you be smarter reader that what i learn from my aunt and other people out there . if you miss reading books and still can doesnt matter what age you are and how you look from the outside. 

You allowed a snob to choose what you were, or weren't allowed to enjoy reading.  Its best to ignore such people and read whatever you want.  Also, hang-out with your own comics-loving crowd both online and offline.  Lastly, here's where you can catch-up with your comic reading that you've missed.  

https://www.comicextra.com/

https://www.mangahere.cc/

Not being true to yourself,  if you enjoy reading comics do so.

You listened to others and allowed them to dictate your actions. I wasn't allowed to read comic books. According to my mother only stupid people enjoyed them.

When I was a kid everyone read comic books, the nerds were the ones that came to school dressed as comic book characters

It depends on what you did instead. If you used that time to apply yourself to your schoolwork, none.  If you started torturing small animals you should have stuck with the comic books.

You caved in to peer pressure, and gave up something you liked just because other people ridiculed you.  I was called a nerd for playing video games and liking computers in my day (idiotic to young folks today, I know)...so we all went through it in some way!