There is a multitude of reasons to as to why a wheel can come off your vehicle but whatever the explanation; the outcome can be extremely dangerous for not only the driver and passengers, but also other vehicles on the road, especially if it happens on a freeway/highway.
This driver of what appears to be a Hyundai Galloper, which is a rebadged version of the Mitsubishi Pajero 5d built by the Korean maker from 1991 until the early 2000s, lost his rear, right wheel while trying to overtake a car and a truck.
The large SUV almost tipped over, but fortunately, the incident ended without a crash. You can watch it as it happens in the video below.