I do wonder what percentage of revenue they are. I expect it's very outsized relative to usage (e.g. approximately nobody who is receiving them is paying for those summaries at the top of search results)
via Anthropic
https://www.anthropic.com/research/measuring-agent-autonomy
this doesn’t answer your question, but maybe Google is comfortable with driving traffic and dependency through their platform until they can do something like this
Nobody is paying for Search. According to Google's earnings reports - AI Overviews is increasing overall clicks on ads and overall search volume.
No ads, no forced AI overview, no profit centric reordering of results, plus being able to reorder results personally, and more.