With his past, it would make thematically more sense for him to become a psychologist specialized in troubled teens or in the use of virtual reality to deal with trauma.
He was obsessed with the game for years. Many games consider going into gaming related careers, its not a big stretch. He is so passionate about the game that he was sad when people were leaving and he tried his best to encourage new players.
also, in any career you have to start at the bottom and work your way up. =)
I'd have been more interested in this season drama if Jaehyun had ever shown any interest in game development, had any formation related to it, his internship at HiGames had anything to do with the game instead of being a cute mascost who gives gifts to users... before it was suddenly his life dream and he left everything behind to chase it.