Just curious how rare or common this is. I’ve been paddling about 28 years and as best I can recall, I’ve only ever flipped in classes (a few times perhaps in surf classes, and once very early on when I was taking a rescue class - we ended up practicing an “all in” rescue). I vaguely recall almost flipping, again pretty early on when I took a stroke with the blade in the wrong orientation and I twisted around too quickly and almost lost my balance due to the lack of expected resistance when blade met water.
I guess the frequency of this is in large part a function of how willing one is to go out in challenging conditions. For the most part, I paddle in protected bays and estuaries, and now a big lake, because those are the kinds of areas I have lived in. But even when I get to the shore (the Atlantic along the southeast coast), I rarely find the conditions to be particularly challenging except occasionally in the surf zone.