Lots of sellers and flippers, apparently. I've only sold, I think, 4 games and that was when I was out of a job. I've spent years trying to get them back.
I did not take this statement the wrong way (at all), but I do wish to elaborate "why" I, at one time or another, got rid of 10 games (which I'd happily have back). There may be others who found themselves in similar circumstances, and possibly some who find this enlightening.
Firstly, I've owned games since 1993 and sold/traded only 10 (all between 2003-2005). What is critically important to understand is it was
a different era. Meaning:
1. My game purchases averaged $100-$150 and were all completely plug-in ready, and worked for years without issue. This was a simple reality of the times. I knew I could ALWAYS get most games (obviously exceptions) for roughly the same stable price. The highest-priced vid I ever saw back then was a fully-restored Star Wars (UR) go for $600 or $650 at auction.
2.
Information was not readily available for collector-hobbyists to seriously handle their own repairs and restoration. Case-in-point, after binge-watching every John's arcade video the spring of 2015, I (then) thought I could do anything. His, and numerous others' videos like his enable thousands of enthusiasts to not only maintain home arcades, but bring others back from the dead. You didn't have this information back then - aside from studying schematics, hard core electronics texts, and/or apprenticing for a local coin-op --all of which are not practical/feasible learning methods for the average collector. Commerce on the internet was also lacking and you wouldn't find the parts you can get now.
Therefore, when your $100 baby broke down, you were forced to pay a coin-op $150-350 to get it serviced. Now, couple that with the unique fact that I was in the military for decades and moved a lot. So, the entire arcade was getting moved all the time (not good) and the amount of dead games was increasing move-after-move. It just got to a point when I needed to freshen the collection and I traded several (cheap) dead games for (expensive) services to get several others fixed, knowing full well I could just buy them all back at a couple auctions, once I settled down, for only a few bills.
To prove my point, when the collection was refreshed in 2005 (last time I got rid of a game), within a month I stood in front of a beautiful Paperboy (private sale), asking $300 or $350. I played a quick game and declined. It was too pricey for me at the moment--I'll find another. A week later I got a very nice survivor Space Duel for $160, and a month after that, a near mint 4-player Sega Quartet for $240.
These were the times.