so is that something we should prepare for if we want to enter professional writing/comic book making? (the not reading fanfic thing)

Well, it’s your call. It’s not like the LAW or anything. But yes, you absolutely should not be reading fanfic.

I hate saying this because it makes fanfic writers sound like suspects. But I swear, it is NOT the vast majority, it’s a tiny minority that makes it an unsafe business practice. I know a lot of writers who started with fanfic, it’s perfectly legitimate stuff. But pros should not be reading it, honestly.