Rideshare networks, for example, fundamentally depend on the underutilization of cars, which generally sit idle most of the time besides the daily commute and the occasional errand. Airbnb is built on the underutilization of guest bedrooms and second homes, combined with the time and effort of the hosts. Craigslist and eBay are built on letting people sell their “junk”—the stuff that they don’t value anymore—to new owners who might value it more.
