The projectile that recently broke the window of a bus in San Francisco carrying Google employees to work felt like an intrusion from the real world into the rarefied air of Silicon Valley’s technology elite.

The missile came from protesters objecting to creeping gentrification caused by highly paid tech workers, who have pushed up rents and home prices in the city’s Mission district and surrounding areas. What better target than the fleets of WiFi-equipped company-owned buses that ferry workers down the peninsula below San Francisco to the headquarters of businesses such as Google, Facebook and Apple?

Though this is a local dispute, it is also one of those episodes that highlight an issue of much wider significance. Last year brought a subtle but important shift in the public perception of the golden children who have prospered from the latest internet boom.