The " gig economy"--scary words for Americans who rely on a full-time job with benefits to make ends meet. The rise of on-demand platforms like Uber, Lyft, TaskRabbit, and Airbnb conjures visions of a future in which 9-to-5 work is replaced by permanent free agency enabled by digital marketplaces. But the sector is booming and one big reason, according to a new report from the JPMorgan Chase Institute, is that people turn to labor platforms chiefly in months when their primary earnings fall, because of factors such as job loss and variation in overtime pay. For most, it's an effective way of closing a gap that might otherwise result in credit card debt or eviction. "It's pretty clear it's helping offset dips in income," says Diana Farrell, the institute's president. That implies the sector will stay attractive--for its workers as well as its users.