Oh Christ yes, when I was younger and kept concluding that I was 'growing out' of gaming (ho ho ho, silly boy) I obliterated my collection of games like 3 or 4 times.
One purge involved getting rid of all the stuff I played as a kid (ie my 'foundation' games), all the spectrum titles I used to cherish, the really obscure DOS games I had which actually worked on our crappy 5.25" CGA PC. Probably in favour of SNES/MD/PS1.
Another purge saw me get rid of MD/SNES/MS/GB (NES was never part of my gaming history).I had... ugh.. I had FFII (FFIV) and Chrono Trigger on import (I'm UK, I got those from my local market when they were current, such a waste), stuff like Rocket Knight Adventures, Soleil (Crusader of Centy, which I had from day of release). That was stupid.
The worst was probably when I got rid of all my PS1 stuff. The PS1 was the first console I had from it being released, apart from that only the Spectrum I was given as a Christmas present at age 4 was current, oh and the Gameboy, which I keep forgetting. For the PS1 I had so much stuff... Clock Tower, I just gave that away to a market stall holder. Klonoa, Suikoden, Suikoden 2, Vandal Hearts, Vandal Hearts 2, Azure Dreams, Eternal Eyes, Castlevania SOTN (with soundtrack). I had all that stuff from new. Those were just some of the games, I had no end of kooky titles the likes of which I love (Devil's Deception, Guardian Crusade, Front Mission 3 etc.) That one hurt, I can still remember buying most of them and still remember owning the PS1 from the beginning, when my local game stores only had Jumping Flash, Ridge Racer, Wipeout and Tekken. I've managed to replace a lot of the obscure stuff, but the 'big' ones like Suikoden 1 & 2 are still missing.
On one other occassion I got rid of a lot of 360 stuff and most of my PS2 collection, just kept the ones I could not part with (and some PS1 which I had re-bought), thankfully kept a few interesting titles but again shed a lot of games that are hard to replace.
I'm rebuilding and expanding my game collection, a lot of the PC stuff will be extremely difficult to replace (very small print runs), a lot of the console games will never be affordable, but I am also picking up stuff like complete gameboy games that I didn't own back in the day. Got plenty to play though