Probably the greatest risk, by a large margin, is operator error, that's true. Air tanks, especially, carbon fiber bottles, are built way beyond safe. If you read the engineering papers and the USN testing, you would feel very safe with cf tanks. Aluminum is slightly less resilient which is why the pressure is less, which puts them in the super safe category. Every time man comes up with an idiot proof design, the world produces a better idiot, so there will always be accidents involving someone doing something crazy.