Pew Research, a renowned US think tank, has studied the impact of AI Overviews. It analyzed nearly 70,000 Google searches from around 900 users. The result:
While about 15% of search queries in search results without AI Overview result in an organic click, this rate drops by half to just around 8% in SERPs with AI Overview. Links within AI Overviews are clicked in only about 1% of cases.

Also interesting: While 16% of searches with traditional search results result in the browsing session being terminated, this figure rises to 26% with AI Overviews. Searchers therefore appear to find what they’re looking for more often.
This analysis confirms the assessment of many SEOs that AI Overviews deliver significantly less traffic than established SERP elements. However, Google contradicts the study and criticizes the methodology and data used.
My conclusion:
It’s probably undisputed that AI Overviews, and in the future even more so AI Mode, will lead to fewer users clicking on search results. We’ll have to learn how to deal with this. Interestingly, users seem to actually find what they’re looking for in AI results and end their search. In the future, success will therefore no longer be measured solely by clicks, but also by mentions or citation in the SERPs.