Cause this just happened to my bro. Traveling on the highway and to my knowledge has had low tyre pressure for at least half a year on all wheels.
No, low tire pressure on its own cannot cause a wheel to fall off - or even damage a bearing.
However; the fact that the tire pressure has been low for so long indicates that general maintenance and repairs have not been taking place either.
Low tire pressure causes excessive heat, even to the point of tire failure, wheel bearing failure, Brake Disc warping, soft brake line melting, other heat problems.
If the bearing fails, it can cause the hub to fail and then lose the wheel, which is known to pass the car that lost the wheel. Heat WILL NOT cause all 4 to 10 lug nuts to fail, that doesn't happen, but never say never with a vibrating wheel.