Jacqueline Chan brought her son to a community center near Happy Valley. "I wanted to show my son how to support others, let him know what is happening now and how to support the survivors," she said.

“We’ve always known Cambridge is not the center of the universe,” Mr. Muller said. “If you’re in Silicon Valley, you might make that mistake.”

But if enough good ones do, it stops being a self-indulgent choice, because the center of gravity of Silicon Valley will shift there.