To be fair, there's no indication that he isn't planning to play the games he's collecting. Plus, most of the games he's collecting have been used, which means someone has played them at the very least, which is why they were traded in, or being sold second hand on Amazon or eBay. If those games were really that fun then the original owner wouldn't have sold it, and to be perfectly honest I doubt there is a large population of people just clamoring to play American Mensa Academy, and feel violated and deprived because they couldn't find it anywhere.
Personally, if I can't see myself playing the game I would not buy it, but even if it's not my prime choice of a game, if it has rarity, and it's something I will play, I'll still get it even though part of the reason was because it's rare.
There are of course many collectors out there that aren't like this at all though, and even more egregious are the ones that keeps everything sealed, and untouched. I think these are the main collectors that I would have a problem with, although a hobby is a hobby, so I can't really fault them that much for that.
Collecting is the part of the fun for them, and who am I to say that they're taking away the fun from somebody else when they're clearly having fun themselves doing so. Otherwise, I personally can't accept the idea of people doing it just because they want to make money, but if those people do exist (which they do), then I feel very sorry for those people.