Being valued as a #unicorn used to be something special. Braintree wasn’t a unicorn in 2013, when it sold to PayPal for $800M. OpenTable was barely a unicorn in 2014 when it sold to Priceline , after having seated 570M diners and gotten 7,700 restaurants on board. That’s why Nextdoor 's $2.1B valuation is a real head-scratcher — and why beating up on Uber 's value is a bit much. Here’s why. …see more