Bettas can have hundreds of offspring per spawn. Breeding pet store bettas yields hundreds more pet store bettas. If the big pet stores get hundreds of customers a day, and you see the same fish sitting there for weeks and weeks, how long do you think it would take to sell your hundreds of offspring, without the number of customers? Few pet stores will buy the fish from you, or even allow you to donate them for that matter. They have enough fish on their shelves to sell. (Granted some smaller scale pet stores might take donation, but that's pretty rare.) You can give a few away to family and friends, but that potentially still leaves you with hundreds of unwanted fish in your care. You would need to find a way to properly house them, pay for food, medication, do adequate water changes. In the end it would actually be cheaper to buy breeding quality stock to begin with. Your main source of getting rid of the bettas will be selling stock to other breeders, which brings me back to the point of no serious breeder would ever buy a petstore bred Betta, the same as a dog breeder would never buy a mutt.
I'm only speaking from experience here, you certainly don't have to agree with me. It simply makes more sense. The supermodel thing is fairly irrelevant, too, because we don't have hundreds of kids at one time and sell them for profit. xD