In addition to the above, most of the Os you'll meet have made it through what is an horrendously challenging course. BOC chop rates are extremely high (or were recently) and indeed of my chums, 11 of 13 on one BOC course fell by the wayside and another one of those had a few recourses before going frontline on Mk8. I've heard many people say it's perhaps the most challenging training available to a junior officer just about anywhere - indeed comparisons in difficulty to Perisher have been made.