First and foremost I do not collect sealed games, but unfortunately have interacted with a few people that have. This was my experience with them.
Sealed Collector #1: This guy worked as a manager at EB Games from like 1997 until the mid 2000s and pretty much snatched up anything and everything as soon as the store wanted to get rid of it. He even stashed stuff until corporate wanted it out of inventory and would buy it up as soon as they did this. From working at a game store for almost two whole console generations he amassed a MASSIVE collection of sealed games from the 16-bit era all the way to PS3/360 titles. He had some insane stuff like multiple sealed copies of Panzer Dragoon Saga, several brand new copies of Lunar 1 and 2 on the PS1, and dozens of different sealed PS1 RPGs. I found about this guy on CL because he was selling some stuff (none of this sealed stuff of course) and he insisted on me looking at his sealed stuff which I found a little weird. He then proceeded to brag about all the sealed stuff and liked to remind me how much the last sealed copy of game X sold for on Ebay and also how none of it was for sale. I asked him politely what the point of having 4 sealed copies of Super Smash Bros was and he pretty much responded by saying because no one else does. It was obvious he got a huge ego boost from having so much desirable sealed games and got off on other people wanting his stuff, but not being able to have it. I didn't end up buying anything off him that day.
Sealed Collector #2: I was out hunting for games at a local retro game store and he was talking to one of the store employees about how he wanted to preserve games by getting them sealed and would pay top dollar if he had to. I found his reasons somewhat noble, but he was very arrogant when talking about his sealed collecting, again seeming to get off on the fact that he had sealed games that no one else had.
Aside from my personal experience with sealed collectors, I've heard they're typically a whole other level of crazy and anal retentive that most people don't want to deal with.