Almost every senior citizen I've ever had clean up malware for got it from a malicious search ad. And the tech support scams they continue to list take advantage of tons of people as well.
I've pointed out before that Google happily lists phone numbers of tech support scams on search terms for Windows tech support, but doesn't show ads at all if you look for Chromebook support, pointing you straight to their official contact.
As a note, if anyone would like to see examples of this in action, I can go get screenshots and example links and everything, it just takes a little while to put together, as I would prefer to offer evidence of what I see "today" rather than any past examples I might have.