If buying things didn't provide value to people, they wouldn't have bought it.
Just because I cannot extract monetary value by buying another MIDI controller for my hobby doesn't mean it isn't a worthwhile purchase. If you derived enjoyment from a purchase, it increased your [non-material] wealth and added value.
The same way, Gmail and FB make money by selling ads, but if they didn't exist without ads, it is easily arguable that people would have missed out on a lot of wealth and benefits that comes with those things. I use Gmail, because I extract value from using it. And I pay for it by letting Google personalize my ads and sell them. For me, that exchange is absolutely worth it. If it wasn't, I wouldn't have been using it.
It certainly doesn't increase the wealth of people who are persuaded to buy stuff that really isn't worthwhile for them.