Geez, so you gonna buy 4 copies just to sell those?! >_< You know I don't like that kind of actions, it's like buying 15 copies on a launch just cos there's high demand. If there's no physical copy, people will buy the digital version.(And if you ask way too much for it, people will actually choose the digital version over the one, you are selling.
I won't advice you to get multiple copies though, I am sure as Rydian stated, that the game will be around for a longer time then the others.