Google cofounder Sergey Brin told public radio's Marketplace that around one percent of all Google searches go through the "I'm Feeling Lucky" button. Because the button takes users directly to the top search result, Google doesn't get to show search ads on one percent of all its searches. That costs the company around $110 million in annual revenue, according to Rapt's Tom Chavez. So why does Google keep such a costly button around?