I'm geniously wondering (but not too hard I admit) what part about theses stories of 'million dollar videogame cardridges' are trues and wich are urban legend.
There were multiple alleged scam story about this 'milieu' and stories about crazy prices were indeed fake (or more exactly PR for derivated product like 'expertise' and 'unusual placement and money laundering friendly').
But I wonder if there is really a market of people exchanging game copy for really high amount with 5 or more digits. (no doubt for dedicated fans, I know a few, but event if they pay hight sum we are still in the 3-4 digits sums and often a lot of time, it stays a hobby).
People passionated about a specic game, willing to pay hundreds of dollar for a legit cartridge and nostalgia kick not doubt.
People willing to spend thousands of dollar on an occasional project of making a restoration of an old arcade cabinet, not doubt (it's a nice tinkering hobby, but the hobby part is probably the most important, not the result).
But "numerous insanely rich and anonymous peoples willing to spend millions on black market with shady people to buy stolen video game cartridge" I doubt ^^