“There are fifty or so billionaires and tens of thousands of millionaires in Silicon Valley.” Think about that for a second: tens of thousands of millionaires, almost all them created by companies that didn’t exist two decades ago.

The defining difference between Silicon Valley companies and almost every other industry in the U.S. is the virtually universal practice among tech companies of distributing meaningful equity (usually in the form of stock options) to ordinary employees. Before companies like Fairchild and Hewlett-Packard began the practice fifty years ago, distributing stock options to anyone other than top management was virtually unheard of. But the engineering tradition that spawned Silicon Valley was much more egalitarian than traditional corporate culture.