Companies give Google and friends free unfettered access to your highly specific usage data that can be used to uniquely identify you, all without your consent or knowledge, and no way to opt out. In exchange, said companies get metrics on how well their ads are doing.

It's ingenious. The incentives are set up entirely against you. The people who know and care the least about privacy decide what to do with your data, and they are enticed to hand it over by the promise of tracking ad spend, i.e. the promise of making their jobs easier and of making their success quantifiable.