If you strip out the stupid things that pilots do (like running out of fuel) then the risk is much lower than the "motorbike" figure. Probably an order of magnitude lower.
The real question is: how do you avoid doing stupid things like running out of juice? The fuel management practices in many flying schools leave a lot to be desired. You have to be really conservative in the way you do things.
I've done many thousands of miles on motorbikes and would not go on them today - too many half blind drivers on the roads. In flying, it's down to you - except when you are given a badly serviced plane and something falls off, and that's very rare. You can greatly improve the chances of that one too, by refusing to fly something that is too knackered. You may have to pay a somewhat higher hourly rate though
