It's a virus for mobile operating systems. It's a decentralized, encrypted, messaging app. It's a distributed data-driven dating site over its own blockchain,and it knows you as well as your phone does, which is better than you know yourself. By the time antivirus software catches up, users are having too much fun, and they'd do anything to keep the application, even switching to a cheaper, less secure, less profitable phone.
After a while phone makers stop trying to erase the virus, just like they had given up with a few dozen other apps.