The bigger issue is "why is it that companies can make more money selling personal data
about consumers than selling products
to consumers?" If companies had a viable business model that involved ordinary consumers paying money for services rendered, then their responsibility would be to the people paying them money, i.e. the consumer.
This is a really complicated question, and probably results from a combination of:
1.) Consumers not having disposable income at all, because real wages for a large slice of the population have been stagnant or falling for a generation and necessities like housing, education, and health care keep going up.
2.) Consumers having certain expectations of what they can get "for free", and not wanting to pay money for things that competitors will offer for free.
3.) Consumers having a poor understanding of the long-term consequences of putting data out there, and what it can be used for.
4.) Network effects where even if a small minority of consumers are aware of the above and would rather pay for products, they can't because a majority of the market would rather pay with information rather than money.
If you just ban the sale of information outright, you will either end up with work-arounds (eg. Google doesn't sell information, but it sells better ad-targeting and behavior manipulation based on that information), or consumers will lose access to services that they depend upon for much of their daily life.