A blog writer who injects ads cares in an analogy similar to how a low-level street dealer cares about pushing to clients. It provides the income. Further up the chain it goes much further than just ads, up to state actors who try to influence elections all across the globe, based on such data. And with AI a new Wild West wide open to explore.
I would consider making people to vote for a criminal dictator to be more harmful than selling drugs, the former is destroying way more lives than the latter. And I am someone who would vote for more enforcement and regulation of bans on drugs.
