Korchnoi was very capable of fooling himself. If he thought he was playing a ghost he'd expect the play to be old-fashioned. Another possibility is that whoever was playing him was using openings etc from previous Maroczy games therefore of course they'd seem old fashioned.
Yes, Korchnoi may have been predisposed towards the idea of the supernatural. However, that does not make him a sap. He was ranked 3rd in the world. Just because he believed he might be playing Maroczy does not mean his powers of analysis went out the window. Korchnoi could just as likely believed Maroczy had been paying attention to chess in all the years since his death. We would have to personally ask Korchnoi what he thought. Absent that, all we have are his own words and conjecture about his state of mind.
Why not? Well you give one possible answer to your own question: 'painfully obvious early on that the world could care less about the game'. Ie there was little to be gained by it.
Then why spend 8 years playing the game at all? If there was nothing to be gained by it, publicity-wise, why waste 8 years playing a meaningless game?
Also if it took 8 years that would seem a hell of a lot of effort so I can quite understand why they didn't do it again.
It was a hell of a lot of effort for no monetary or publicity gain, which would have become obvious very early on in the game. Not only would they not have done another game, they wouldn't have finished the first one! How hard would it have been for the medium to have "lost contact" with Maroczy? They ceraintly wouldn't have done all the research that required travel to Hungary and interviews with Maroczy's family.
I was a very average chess player but often beat superior players by a combination of confidence and aggressive style. They'd fool themselves into thinking there was more behind my moves than there was and waste time countering a perceived threat that I wasn't even aware of. Psychology plays a large part in chess - especially at this level. You don't just analyse your own moves ahead but your opponents and if you think your opponent is a good player, you'll work out good moves for him from the current position.
Hmmm, just a wild guess, but you're experience playing Grandmasters is probably nil (doubly so your experience of playing one of the top ranked players in the world, but this is the internet, so feel free to claim otherwise). Also, a game by mail is rather dry and abstract. Not as suscetipble to the kind of psychological tricks you could employ.
This is just a supposition on my part, but I'm pretty sure that even if you played "confidently and aggressively" against the 3rd best player in the world, you'd have your ass handed to you in short order.
You're assuming Korchnoi spent all his time between moves thinking about that game.
46 moves over 8 years? One move every ten weeks? Yeah, it's likely he spent some time thinking about the game. I would guess about as much time as the mysterious gifted chess player the medium and Eisenbeiss were in contact with. Oh wait! I forgot. Eisenbeiss had access to a high-ranking chess player who had absolutely nothing better to do than spend the entire day studying the game!
I'd suggest that someone with Korchnoi's profile would be busy with other things (and indeed other games) whereas his opponent may have had considerably more time to spare on this as it would probably be the only game he was playing.
If Korchnoi's opponent could make Korchnoi, 3rd ranked player in the world, doubt the outcome of the game, Korchnoi's opponent would ALSE be busy with "other things (and indeed other games)". Ah, but I keep forgetting- Korchnoi's opponent was a skilled enough player to nearly beat a Grandmaster, but had nothing better to do than analyse a game because a medium asked him to. That's VERY reasonable
Oh, and to top it all off, AFTER it became clear the game was getting no publicity and no money was at stake, they spent 70+ hours of research on Maroczy's life, travelled to Hungary, interviewed Maroczy's family, and studied old chess programs. That's also very reasonable.