Now you have 50 million people's data for sale. Are you in that 50 million? You don't know or you will never know.
Connected incidents - British Airways Data Leak, Equifax, Uber Data Theft Cover Up, Air Canada, T-Mobile, Dixons Carphone......how many such. All of them soon will be available for sale, with no one to blame for.
I don't think there has been much stopping these companies selling the data up to this point. That's been the issue with Facebook and others, they have happily sold peoples data with little legal protection for the people whose data they sell. There is no crime in just selling the data within the US so your theory doesn't hold up.
Never attribute to conspiracy that which is adequately explained by incompetence.