When the ride-sharing app Lyft rang the opening bell at its IPO in March, pink confetti rained down on the trading floor, a reference to the company's current pink logo more than its long-retired one: a furry pink mustache that sat atop drivers' cars. The wacky mustache was emblematic of Silicon Valley's live-for-the-moment startup culture, where entrepreneurs focus on quickly scaling their product to millions of people, prioritizing high user growth over immediate profitability.