If I counted up all of the games I've had since the Atari 2600(my first system), I've probably had more than 1000 and likely double that considering all of the ones I've sold, rebought and tried to rebuy over the years.
Back in the 2600 days though, I was like kids nowadays and I kept the games cart only. But from the Genesis/SNES era on up, I tried to keep my games in mint/complete condition and would actually nitpick on condition when I lent one to a friend(and I still do now:-#).
You have to be man. You never know when you'll want to play those games again. Shit, I probably owned close to 400 since I started gaming. I started gaming at age 2 with the Super Nintendo, and Sega Genesis. After that I owned a Playstation, Gameboy, Gameboy Color, PS2, PS3, PC, and Xbox 360. My sister owned the Xbox, Dreamcast, and Gameboy Color. If I could count all of the games I owned/played it would be around 400 games total. If you add in cell phone games, that number would go up as well.