It happens to me too now and then and I'm pretty sure that we're not the only ones. The Ad icon I see is far from gigantic and more blueish than gold, it's very easy not to notice you're clicking on an advertisement. Maybe15 years of using Google and relying on the first search results on top has caused some sneaky "Ad" blindness.
Sometimes I feel sorry for the advertiser when I accidentally click such sneaky text Ad, especially when the first real, natural search result is the link to the advertising company's website, just below the Ad. It feels like a devious way to rip off advertisers who would have been first anyway.