Once, I was sawing down an old dead locust tree that I wanted to use to make fence posts when the vibration from my chainsaw caused a high limb to break off and fall from about 50 feet above.
That limb, about 4 inches in diameter, missed my head by about 2 feet. Using a handsaw or an ax, I might have heard the crack of the limb when it broke, but the roar of the chainsaw drowned out all other sounds.
A few years ago, I was sawing up a downed tree for a neighbor when, with the saw running, I tripped over a piece of junk metal hidden in the leaves. Having worked in the woods for years, I had the presence of mind to extend the saw away from my body as I fell forward. I sprained my other wrist (with which I broke my fall), but the situation could have been much worse.
We all tend to do stupid things at times, especially if we are used to handling power equipment. Forty years ago, I had a friend whose truck was hung up on a log and he decided to crawl under it with his chainsaw in order to clear the obstruction.
The saw accidentally hit the metal of the truck, flew back and cut him pretty bad. Luckily there was someone with him, but had he been alone, he might have bled to death.
I have seen people stand on the back of pickup trucks (I’ve done it myself) to cut overhanging limbs in their yards. Not a smart idea, but it happens all the time.