Main issue is that they control a lot (most? 99%?) of the video and webpage ad market. Dunno why nobody else is getting into those markets.
If you're not running a multi-million $ site, you're especially screwed for alternatives unless you're selling something and can get affiliate revenue.
If Bob wants to put up a video fixing vintage washing machines, he'll have to do it out of 100% altruism, because Google is going to take all the ad revenue.
If by some miracle you managed to start a successful business in that area, they would just buy you. Even with the new anti-trust scrutiny, they have no trouble buying small companies and startups.
Why not? Probably the cost of these occasional bans are nothing compared to the reach of the ad network.
(Not that I recommend using it. I recommend the old fashioned ways of knowing where your banner ends up. And make sure it doesn't become one of 344 on some random site. So build partnerships, etc. Yeah, it sucks, it's work.)
You're arguing with an "average return" but as a single person you only play once, or in any case a small number of times if you're willing to sign up for new accounts. So the variance of your results, paired with the impact of an unfavourable outcome, should probably figure into that decision...
I think you'll see similar problem in other similar growing or already big tech companies. It is important in that case to have the user's rights protected at a general -national- level.
If you're not running a multi-million $ site, you're especially screwed for alternatives unless you're selling something and can get affiliate revenue.
If Bob wants to put up a video fixing vintage washing machines, he'll have to do it out of 100% altruism, because Google is going to take all the ad revenue.