The market is expecting a lot more from the young growth stock.The market has finally been cheering PayPal (PYPL 1.46%) again. It's demonstrating progress under new leadership, and PayPal stock is up more than 15% during the past six months.But several billionaires have been piling into lesser-known fintech stock Bill Holdings (BILL -0.77%). Bill is a younger company with lots of growth on the horizon. Should you take a chance on it?Billionaires like BillBill provides software-as-a-service financial solutio ...