I have heard said that the older a helicopter pilots gets the lower they fly.
I have done those 10,000 foot cruises seeking some cooler air in the tropics and at the same time have been quite content to do the same trip at 300 feet.
There is no doubt you can see more low than you can high especially if scouting for Elk and Black Bear with an approaching hunting season coming up.
Reading railroad, highway, and water tower markings is far easier from 300 feet than 10,000 feet.
As to malfunctions at height....once had an abrupt engine failure at about 9,000 feet AGL....it still seemed like mere seconds before landing.
I know in my heart that is way too high for such things as it affords you far too much time to think....as helicopter pilots and with too much time to think often leads to trouble.
The rare event of a major cast iron failure such as a Main Transmission or Rotor head catastrophic failure....the odds are not much different if you are at 10K or 300 feet except for the fact you might live just a bit longer from way up high but I doubt the quality of that extended life would be much improved over the short duration from the lower height.
If you dwell upon such things perhaps helicopter flying is not your best choice of careers.