My definition of a hoarder, that is probably far more common than you can imagine (or maybe not - it's easy to imagine round here) is someone that has had the word "No" surgically removed from their vocabulary and therefore has a games room (or two) that is so packed full that you can barely get to the games, let alone ever stand any chance of getting them working and playing them. Never mind the fact that they probably have storage full of them too.
Come on then, own up, you know who you are!!
Typically, a classic tell-tale sign of the hoarder is that they're also in denial, occasionally tweaking a couple of games, getting them so you can play 1 or 2 and doing so for a couple of evenings just to kid themselves the games can be played, before ramming more in and completely negating that effort for another 6 to 12 months.
Wonder how many people that sounds familiar to??
I voted 'Gamer'. I don't really play them much but I have a small amount of quality games, all bar 2 of which are fully working all the time and there's virtually always plenty of room since my games room is also my office. Therefore, I am not a hoarder by any stretch.
If you peek in the loft at the PCBs, well, that's a different story but I suspect it is for most collectors.