Take for example when we did the Everest Base Camp Trek. Steve got really sick during the hike and had picked up the infamous Khumbu cough from the dust in the thin air. As the days went on, he got worse and worse, and as we were about to embark on our final day hiking 9 hours, he could hardly move. We decided very quickly to get him an air ambulance out of the trek because we thought he had pneumonia.
Luckily we didn't have to think twice about paying $1000 for that helicopter because we had travel insurance with World Nomads. Within a few weeks, we luckily got that money back in our pockets.