Question about the fundamental idea of Datum: How will the prices/value of individual data compete the incumbent data broker prices/values? Is the data people would be selling not already available through data brokers at a far lower price?

At first blush, this idea seemed awesome. Now I can make money from data of my Facebook/Echo/Gmail etc by opting into datum and reselling on datum's marketplace. But then I realized that by dong so, I don't necessarily opt out of ongoing data collection by those platforms (there's often no way to opt out). So the data is now redundant; i.e. the data is for sale in two places, and my guess is the data brokers price is a going to be pennies. If so, there's no/little incentive for me to sell it on my own.

Is the idea that this marketplace would be used far in the future when services exists where we can actually opt into and opt out of various collection services (including datum)? As far as I know, most of the major platforms that collect data wouldn't allow me to fully/significantly opt out?

Different question: Will there be an option through datum to supplement our data sets with additional demographic information, or answer other questions from the data buyer, to make it more valuable?