Airbnb's earnings have taken off in quite an impressive fashion. The cherry on top is that insiders own a bucket-load of shares, and the CEO pay seems really quite reasonable. The sharp increase in earnings could signal good business momentum. Big growth can make big winners, so the writing on the wall tells us that Airbnb is worth considering carefully. What about risks? Every company has them, and we've spotted 1 warning sign for Airbnb you should know about.