when your collection takes over an entire room is a good way to tell your a serious collector lol
It don't matter if you collect loose or Complete.
If you have love and passion in your hobby and love not only the games, but the art, the history and the hunt for adding new games to your collection. Then in my books your a serious collector.
Every collector is different. Some only collect one brand. Like only Nintendo or Sega. Others only want to collect what they think they want to play. Some are anal retentive and must have all their games brand new in the box sometimes sealed. While others just want a copy of the game to play and it could be loose and look like crap.
To me a serious collector just has to have a love of what they collect, they don't care if it is worth $1 or $1000, to a serous collector its not about what is valuable its about what they love. If anyone here is collecting video games as a investment your in it for the wrong reasons. Most collectors I know are about the hunt for deals and not paying stupid prices, its part of the fun trying to get deals. I love garage sales not just for the deals but because I never know what I'll find and bring home. Its part of the fun.
Everyone on this forum is a serious collector of some kind, you wouldn't be cataloging your collection and wanting to talk to others who enjoy your passion if you weren't. While there's different levels of collector's, we are all serious in our love for old and new games.