I would look no further than the basic ingredients of the sport: speed, gravity, zero margin for error and over a long enough run of events you are destined for the morgue. This is not a sport, it is suicide in disguise.

One more thing: it's turned into a small industry. Some of the work in it I am certain is considered to be partly art (I am thinking of the analogy to the sailing industry in the early years of yachting). I wouldn't rule out a look to "advances" in suit design where the new engineering has an unforeseen consequence. Something the advanced guys would jump on board with, but we don't have enough data yet to determine the failures.

Does experience grow the margin of error? Do "incidents" become less fatal? Like in Russian roulette, its possible that experience doesn't improve your odds when something bad happens.

Sky diving is a little different, if a chute fails to open, your ability to remain calm and deal with it and deploy the backup makes a difference. In a lot of extreme activities I could see experience making a huge impact during incidents, flying suits might not be that forgiving.

It could just be the non-linearity inherent in flight. Or perhaps being in proximity to the surface causes the Reynolds number to be more variable, meaning 10 experts could do the same maneuver and have different outcomes.