Gathering data from a million people on which shade of red makes them more likely to click a button is entirely different today due to the scale, how cheap it is to setup, and how cheap it is to tweak. This data can then be used to "nudge" people towards a direction that you benefit from (and they may or may not benefit from, and society at large may or may not benefit from). At scale, these very small nudges can have an impact. The unregulated methods we use for this keep improving (AI).

Not to throw shade, but there's a reason why Amazon has been hiring behavioural psychologists. We should be aware and thinking about this.