Electric scooter-sharing company Bird has raised $400 million in four months to cover the streets and sidewalks of America with scooters. Plenty of people in Silicon Valley have been scratching their heads over the $2 billion valuation that Bird has gained in a year since founding. We asked investors at Sequoia Capital and other VC firms why they backed Bird of all the scooter startups — and how they justify the $2 billion price tag. VCs said they believe in Bird's CEO, a former Uber exec, because he invented the scooter-sharing market and has the experience to scale the business.