No one. She could have spent another 8 years doing absolutely nothing with the patent. I don't think that's the main point of the article though, it's just trying to show how an inventor of something is not necessarily the person benefiting financially from their invention.
I'd love to know how it became popular, which the article doesn't really address. It seems like a fad, which would just be dumb (bad) luck. But if Hasbro, who had decided not to produce it, intentionally sat on it for eight years then manufactured and marketed it, that would be deplorable.
