Ha, you're the only person I know who consistently buys multiple of the same LE ha. 
I probably would, too, for the right game and if I had the money and space for it. As it is, I don't have space for the single collector's editions I'm already buying.
Eh...I actually *don't* do it for anything even close to every one -but- I'm pretty good at (by now) knowing pretty much the ones that are almost certainly going to rise to double, triple, etc their original prices...the 'worst' I've ever done on one is to break even.
Pretty much, what profits I make like this = the amount of $ I spend on my own collection & future speculations.
*Keeps kicking self in ass for missing-out on the Wizard's Edition* :'(
PS
There's also been a lot of times (like w/ Darko recently) where I wind up using extra copies (AT COST...*NOT* doubled *cough*Scott*Cough*
...helping out friends who may have missed-out on something
I'm definitely glad I was able to get the Wizard's Edition when I did - I have to thank VGC for that as I probably wouldn't have even known about the game otherwise. And I feel really bad that you didn't get the Ni No Kuni LE, esp after they had the "second wave" of sales. Really, really unfortunate for many people.
In any case, I'm thankful that I have one in my possession while watching its price skyrocket. I have other LEs that are doing ok (ex: Skyrim, Persona 4 Golden, Virtue's Last Reward), but the whole craziness of Ni No Kuni is insane. People are selling just the plushie for $50, even...
But yeah, I hear ya - sometimes I buy additional copies in case any of my friends wanted it but weren't able to get a copy. For instance, I gave a friend one of my VLR watches since she wasn't able to purchase the game when they were still coming bundled with that bonus.
Speaking of which...
http://www.aksysgames.com/2013/02/12/have-a-nice-trick/
