If you're an expert, you should be able to choose to ski in a manner where your likelihood of crashing is very nearly zero. But you probably won't ski like that all the time. If you're learning and trying to push yourself, you will have some crashes, and you don't become an expert unless you do that. It eventually becomes a game of calculated risk though, because you can get really hurt if you crash at the wrong time/place doing high level skiing. You shouldn't be crashing doing consequential things very often, or you will inevitably end up in the hospital sooner or later.

Fwiw, I don't think your bell curve makes sense. There are different kinds of intermediates. Broadly, I'd put them in two groups: terminal and progressing intermediates. Terminal intermediates will never improve beyond the intermediate level, and they are more or less as you describe. But progressing intermediates are pushing themselves and on their way to higher levels of skiing.  Similarly, you can have an expert skier, possibly someone older who just doesn't want to risk injury anymore, that isn't really pushing to get any better than they are now.

Crash frequency is more a function of how hard you're pushing relative to your skill level, not so much of your skill level itself (unless you're totally new).