I think there's a big difference between these two things: > 1: Using customer data to improve your product, to make them happier paying for it, which makes $$

I think there's a big difference between these two things: > 1: Using customer data to improve your product, to make them happier paying for it, which makes $$$ > 2: Using customer data to sell to someone else or to sell the user's attention, which makes $$$ The extra level of indirection through a product that you deliver to the user that provides value to them makes a huge difference between these two ethically. That said, I will admit that a company can move from 1 to 2 completely seamlessly, without the knowledge of the user. A bean counter, unscrupulous wallstreet exec, or changing priorities may take something that was intended to only ever be 1 and turn it into 2. This risk may be too high for you and that's your call to judge, but I find it hard to fault a company just for trying to improve their product. I do wish more companies took Apple's "differential privacy" approach which allows the data collection technology itself to draw a hard line between 1 and 2 that can't be crossed invisibly.