Sean Harding downloaded Whatnot, a live-shopping app, after rekindling his childhood baseball-card collecting hobby. Within four months, the 45-year-old accountant had spent almost $1.4 million—from his savings, personal loans, money borrowed from a friend, and finally his employer's company credit card. When his wife discovered the full tally, she filed for divorce. "I just kept telling myself one more time, then I'd sell it all and make all my money back," Harding said. "But it was so easy to just swipe right.

You don't even remember how many times you've done it." Whatnot, now a seven-year-old platform, is one of the fastest-growing shopping apps in America. It hosts high-energy live auctions around the clock where users bid on trading cards, squishy toys, designer fashion, instant ramen, and nearly anything else. The app's feverish 'breaks' and fast-moving auctions hook users hoping to buy prized items, often leading to compulsive spending with devastating personal consequences.