Most of the pet store bettas are shipped in from fish farms in Southeast Asia. I also believe there is a Fish farm in the US (maybe WI?? I'm not sure exactly).
Personally I don't blame the breeders. When it comes to fish farms its a livelihood we're talking about. You have to remove the emotion from it.
Unlike, say puppymills.. where the dogs are rife with genetic and health issues, a fish farm produces healthy stock. You can't breed sick fish so I know that before coming to the pet store the fish are healthy and well cared for.
Its hard to imagine why people could let the fish suffer but honestly they probably don't know the extent of how the fish are treated, and on top of that they rely on pet stores to buy their stock to help support their families.