Is there some waste? Sure. But certainly no worse (and likely better) than small businesses who don't have the volume who are paying for clicks without proper incrementality based measurement.
Small/mid sized adtech (and eventually any not directly attached to a platform) can't do shit anymore. Small/mid sized customers therefore have to go to the bigger platforms (YouTube and Facebook, notably) to get anything decent.
They're paying more for less, and power is concentrating in the big adtech players further. The flip side is, security of personal data is on average significantly better. But overall privacy seems like a wash or marginally worse, to become significantly worse once monopoly abuses kick in.
They're just a different channel.
That conversation you overheard in the elevator? That 'chance' youtube video linked to you? Some on twitter making an off hand remark? That visit to a website or a physical store with your smartphone?
All of these and more are part of paid campaigns.
I hope I'll never see it happen.
Also, I don't trust any brands. Maybe that's because I was born and live in a post-soviet country but I assume everyone wants to rip me off.