That does matter. It costs money for companies to place adds with Google. That money goes directly to them regardless of whether or not you make a purchase. They then make use of their vast data resources to target people with said ads, which may not affect you, but definitely pushes products (some business people have described a 3x on investment with Google and Facebook ads).

Because Google ads are on nearly every website, and because Google owns such a large bevy of services including search, YouTube, Gmail, and maps, they can collect all of this data into a scarily accurate profile of your behavior, interests, and beliefs. Data that is shared with their partners and ends up all over the internet.