My Dreamcast collection is my pride and joy.
I may buy a couple of these games again, but I don't see myself selling off any of the ones I already have.
I was talked into selling my Genesis back in the day to get some cash to put towards a new system. I still regret that one. A few of the games I had still aren't out for download, and I'm one of those guys that likes having the physical media. It looks nice, you've got the manuals/packaging that usually have some pretty nice artwork, plus it gives me more of a sense of actual ownership. It's kinda dumb, but I feel more like I own something if I can hold it in my hands.
It's the samre reason that I still buy CD's instead of just digital downloads of music. It takes up a stupid amount of space, but it's just the way I am.