As capitalism does another ideological reset the excuse du jour is that the credit crunch was a highly improbable event, a “black swan” (it’s not just a bad song by Thom Yhork).
If this is true then the people who sold unsustainable mortgages to get the commission on them then sold them on rather than take on the risk of those mortgages were behaving irrationally, because they could not have foreseen that anyone would default on them. This would raise more questions than it answers.
The problem isn’t probability. The sub-prime market was exploited in the way it was because of its probabilities, not despite them. The problem is greed. And self-pitying denial won’t disguise that, however dense the notation.