If I go round giving people the 'choice' of free samples of heroin, with full knowledge that they're highly likely to become addicted and will no longer be able to choose not to parttake, and even with the intention that they do, and then I make bank, that's pure exploitation. And detriment there is definitely not subjective. Maybe there's a little more nuance to the equivalent in social media but it's not all that different, and negative effects on mental health are even more scary because they're not as blindingly obvious as the results of a physiological addiction.
Maybe you should try understand the limits of rationality in human decision making, especially with immediate vs. delayed rewards, then you might get some idea that choice is often more a function of the options in front of you than whatever might have the best outcome. Reality is just a little more nuanced than this oversimplified ECON101 libertarian ideal of absolute freedom of choice.