While everyone understandably freaks out about the skyrocketing cost of living in San Francisco, Silicon Valley’s where the real wealth is. Of the 71 billionaires who call the Bay Area home, seven have their primary residence in Atherton, a small town with a population of less than 10,000. Because of Atherton’s unique location and exclusivity, the zip code 94027 in the town is now the most expensive in the entire country. Let’s do a quick compare to San Francisco. The median sale price for San Francisco in the last 90 days is a jaw-dropping $950K. In Atherton it’s $4.59M. The median list price for Atherton is even crazier at $9.44M. Why is Atherton so expensive? In short, it’s the nicest and most exclusive place to live in Silicon Valley. You also might get a neighbor like Google’s Eric Schmidt, HP’s Meg Whitman, or Facebook’s Sheryl Sandberg. It takes less than 20 minutes to drive to Facebook, Google, and the other major tech companies in Silicon Valley. Another key factor is inventory, which is low. When a property does come onto the market, it’s likely to sell for tens of millions of dollars.