Now I don't know anything about the world - and the best cure for it would probably to get rid of every single human being and it will instantly solve about 97% of the problems. If it is all about saving bettas, then the source of the evil needs to be eliminated. No, no, not talking about the humans again, but the pupp... aehm betta mills that mass produce them. You cannot honestly expect a law to get passed that would make it illegal to sell betta (or any fish) in a small cup. How exactly do you think fish get shipped even to the nicest of stores? Make it illegal to sell like that and nobody is going to have access to bettas (or most aquarium fish) any more.saving bettas isnt about logic its about saving the betta and saving the world.
But it is about saving the bettas and the world. Start with the humans, and see what is left to fix.