You're missing an important nuance. The best advertisement is for a product that,
in expectation, makes the most money from me. My relative interest is still important, and you can't just jump from the fact that somebody is making money to the unfounded claim that the "expected utility is negative."
When I buy an item I'm making a decision that the marginal value of that item to me is worth more than the marginal cost. If the ad is targeted, a transaction is more likely to happen. Transactions happen when both parties derive utility from them.
If you advertise only high profit items without concern for the probability of transaction, your audience will not buy anything or end up buying the same item from somebody else.