Years ago I watched my ex restart a motor that had stalled on an old little aluminum fishing boat out in front of the cottage (old motor with no kill switch option) he went to sit back down and lost his balance and toppled over the side (was stone cold sober).
The engine did start before he fell and once overboard the boat took off running full throttle. Because he was starting it right before he toppled the engine was turned so it circled back around literally DIRECTLY back at him, had he not been in waist deep water and able to sort of fend it off it would have run him right over. (Life jacket would have done him no good).
15 years later he still has shoulder problems and a scar on his forehead from that, from the force of it coming at him and him pushing it away and still smacking him in the forehead..... and he is a big guy. We watched it circle around and around for about 10 minutes getting closer and closer to other boats and thankfully swimmers had left the scene. Ultimately threw an anchor line at it until it finally fouled the prop.
I couldn't imagine not having one after witnessing what was almost a horrific and gory death. he was very lucky he was in shallow water when it happened and luckily no other boats were hit. Scary stuff.