Working on the conservative assumptions that an average person will run 10 searches a day and click on 1 search ad a day, Google will make $83.39 a month from the average user. It is likely much more though.
I highly suspect the distribution is not flat in any way though (some users are much much more valuable than others and it's why advertisers pay FB and Google to target the ads for them).
-----
[0] https://thecorrespondent.com/100/the-new-dot-com-bubble-is-h...
Based on the linked study [0], 57% of people can't tell the difference between a Google ad and an organic search result.
[0] https://varn.co.uk/01/18/varn-original-research-almost-60-pe...
Still think the business opportunity for a really good paid-for search engine is there. Of course it's not trivial to make a search engine but as I feel Google's usability is in a falling trend, the bar is getting lower..
Source: https://ig.ft.com/how-much-is-your-personal-data-worth/