Video games have always been a big part of my life, but collecting for me I feel started during the end of 1999 and the early 2000s. Even though comicbooks were my main focus during this point in time, I used to go to Babbage’s and Electronics Boutique regularly to get my video gaming fix. Going to the arcades was also a big thing for me back then, which also solidified my interests. My friends from school were also a big influence; if it weren’t for one of them, I would have never discovered Pokémon (and ultimately become as obsessed as I am today with the franchise).
College was also a big factor given I met new people with the same interests as me, including video games. Also, I've been collecting a lot of things growing up (even rocks), so the mindset was there already, I guess.
If I'm being honest, though, I think collecting is essentially the natural evolution for every gamer...or at least those who are the most dedicated to the hobby.