I may be one of the old timers who has been collecting, on and off, for about 24 years, starting in 1992. In that time span I've bought and sold two MASSIVE collections consisting mostly of pre-crash systems. I sold my first entire collection in 1996. I started collecting again in 2000 and sold that entire collection in 2005. I regretted getting rid of everything shortly after both sell-offs.
I started in 2008 on my third collection, this time vowing to just buy games and systems I enjoyed but also to not sell it all again. That first part, about only buying games and systems I enjoyed, lasted about a year. In 2009 I started making youtube videos (which I haven't done for several months now) and getting reactions to people watching my pickup videos encouraged to buy anything and everything just to make some damn pickup videos. Around late 2011 and early 2012 I took stock of my collection and how it was getting so out of control, how I had so much fluff and shelf filler, most of which I NEVER played, and I started a big purge of all those systems and games I didn't play. I did a similar but smaller purge in the summer of 2014.
As of yet, I really don't regret anything I've gotten rid of and I think THAT is a testament to how much of my collection was really unneeded and unwanted. I am glad I've made videos over the years as I still have a record of my collection at various points over the years, at least of this third collection. I wish I would have taken more pictures and videos in the 90's and early 2000's when I was hunting regularly, during those first two collections when it practically rained classic video games, before ebay and resellers. I had some finds, the quality and quantity of which would make your head spin. Think of what Flea gets x 10. I'd regularly come home from yard saling with several boxes and garbage bags full of pre-crash games and systems and most of the time I never spent more than 30 or 40 bucks. Not joking.