When stock brokers were charging commissions this was their model too. They would take the user profile of most of the users that gravitated to their specific

When stock brokers were charging commissions this was their model too. They would take the user profile of most of the users that gravitated to their specific sales pitch, and make a commission structure that worked for them and let that subsidize the outliers that traded different products like high volumes of sub-penny stocks. (There are some fixed costs to stock and options trading, which are now subsidized by selling data instead of charging commissions)