Fish without defects can wind up in a 10 gallon in a lfs, so it's not as if it only happens to fish that do have defects. The way I see it OP loves his oscar, so chances are that it wont be sold off to a random lfs.
What I commonly see is fish that does not make it to a person's standard that gets sold off to a lfs and forced into a tiny tank. Fish without the colors one wanted, fish without the personality one wanted, all that stuff. I find people that commonly choose the fish not for the fish itself but for other purposes like having an extremely beautiful display or want fish to be super entertaining tend to have their fish end up at the lfs.
I personally when I obtain fish, feel that I have an obligation to take care of 'em and not sell 'em off when I feel like it. I would give my fish away though, if I know they're going to a good home. Otherwise no. That being said, the exception is if one of my fish has a disease or has a defect or somehow turns really ugly, such as having an eye bitten off or... a tail. Then I'd prolly give it away right away to anyone or kill it. Simply because I cant stand fish like that, but that's just me.
In the end, we all keep fish to make ourselves happy, whether from their looks, or their personality, or from having them fight each other, or otherwise. So long as one's happy, well what else matters. All we have to remember is that we're all different and we should respect that.