I've never heard of anyone having an ESC fail mid flight. Again, it might happen, but the mean lifespan of a healthy ESC is definitely >100hrs. None of this is

I've never heard of anyone having an ESC fail mid flight. Again, it might happen, but the mean lifespan of a healthy ESC is definitely >100hrs. None of this is even really relevant. GP quoted a figure from a paper that pulls the figure out of thin air and doesn't justify it in any way. The figure can be disregarded. I'm just pointing out that the figure seems much lower than mtbf of any of the critical components of a quad.