> Are you sure ads are "nagging" people as opposed to genuinely changing what they want?

Yes. I'm susceptible to this. I became aware recently. I use and collect fountains pens & inks, and I collected a considerable collection. Unsubscribing from vendors mailing lists, and not visiting related sites reduced my desire to get new things and I enjoy what I have more.

It's same for Humble Bundle's books, and some other items too.

In short, I'm sure. Seeing less advertisements make me want stuff way less, and use what I have more.

At the end of the day, yes, advertisement is manufactured demand. Esp. with all the psychological research behind it.