I wonder how much money is wasted just transmitting ads over the internet. Like I get websites are getting paid for displaying them but imagine how much cheaper things would be if ads weren't jacking up demands for bandwidth.

It's not wasted bandwidth; we've reached this level of ads because brands have realized that brainwashing the populace via ads to make them want their brand is cheaper than building a better product, so the bandwidth is a small price to pay for brainwashing people.

If we didn't have ads, people would not only need less bandwidth, they'd buy less physical junk, and quite possibly be happier for it.

Money wasted by the user on a data contract is a gain for the carrier.

That’s a low bar. Like crypto mining for the power company or throwing extra food out at the end of the day is revenue for the trash pickup company!

Agreed, this is almost a textbook example of the Parable of the Broken Window https://en.wikipedia.org/wiki/Parable_of_the_broken_window

Estimates suggest that between 1/3 and 1/2 of all Internet users in the U.S. use an ad blocker.

Now that we have auto play video ads? Most of it.