> And that's in a nutshell both the solution and the problem because users have only so much to spend on product. I don't see the problem? It's probably much m

> And that's in a nutshell both the solution and the problem because users have only so much to spend on product. I don't see the problem? It's probably much more expensive per impression than traditional advertising, but probably much less expensive per sale (which is the metric that matters). This arms race means that if I'm a plumbing supply company, I can now spend my money on displaying ads for specific plumbing goods to people searching for specific plumbing goods, even when that means I'm going to hit some people no longer in the market for these goods -- but even hitting people who are no longer in the market is vastly better then hitting people who were never in the market. This lowers the barrier to entry (less cash required to advertise your products) which means more and better competition which means prices go down.