Automated ad fraud is why. It's the biggest problem you've never heard of.
The last time I heard it cited (which, to be fair, was a few years back) the actual number was 33%—for every three dollars spent on digital advertising, a dollar gets lost to fraud. Not too far off.
Roughly three years old I think. But if you're referring to the same ad fraud rings I'm thinking of: yeah, a few did get shut down (which iirc was a first) but there's plenty of new operations taking their place. Ad fraud is a relatively cheap way to make money if you can scale up your operation, and most perpetrators don't get caught or punished. Although that may change in the future.
The last time I heard it cited (which, to be fair, was a few years back) the actual number was 33%—for every three dollars spent on digital advertising, a dollar gets lost to fraud. Not too far off.