I've willingly clicked on a couple ads sometime this year when I was desperately trying to find something that neither DuckDuckGo, Amazon, nor Google could find (namely, a very last minute plane ticket for an even remotely reasonable price). My thought being "since the regular results are SEOd to death, maybe the people willing to pay for me to look at their offer are of higher quality". Plot twist: they weren't. But at least that made me realize that my adblocker was disabled so I could at least fix that.