What can surprisingly kill someone?

Boredom.

Chronic boredom can lead to depression and loss of passion. It can cause people to seek out a rise in drama because not enough is happening in their life. It can sit on your shoulders and remind you of all the bad things that have happened. It can also lead people to doing some really stupid things including hard drugs or various forms of gambling.

My mums friend died years ago riding a rubber ring behind a speedboat. He flipped out of the ring and hit the water badly. They all went back to the hotel to get ready for a night out, he said his neck hurt so he was going to stay in his room. They found him dead the next morning.

The force of hitting the water had broken his neck and given him brain damage but somehow he wasn’t in much pain so thought he could sleep it off. Nope.

An air bubble.

Drinking too much water aka water intoxication- not like choking on it and drowning but you can theoretically drink so much water it causes pressure in your skull that leads to headaches, double vision, coma and death

Go Pro cameras on helmets. The mount creates a focused pressure point upon impact and can pierce through helmets. People have died when the camera mount punctures through the skull.