And there it is: They failed because they "didn't work hard enough." It's really easy to classify failures as not working hard enough, and successful people as having worked hard enough.
But what's hard enough? Can we quantify by any means other than the outcome?
We can point to people who have never worked on their business for more than 40 hours a week and their business has succeeded. We can point to people who have put more than 120 hours a week into their business who have failed. Who really worked harder?
You misunderstand the "No True Scotsman" fallacy to apply it to this situation. There's a metric for success (graduating), and no one claimed that the only possible way that someone didn't make it is "work harder". I said that perhaps that's the reason since by the time people make it to medical school, they're on a fairly even playing field.
NTS is typically applicable when someone expresses a goal like "being a good Christian" and then continues to redefine what that means, never admitting that some are good Christians because of endless redefinitions of the metrics.
The 40 hour business success is the rarity and often it's predicated upon other previous sacrifices made so that 40 hours is later sufficient.
As with the xkcd comic, it seems silly to base your success model on the lottery type system that is the rarity rather than on what works most generally.
Besides, it's not always about the amount of time being worked.
Merit is a combination of hours put in, intelligence, the value of decisions made, etc.
I'm not arguing for strictly the number of hours worked. I'm arguing for merit based upon a number of factors vs the idea that all success is determined by luck.
But what's hard enough? Can we quantify by any means other than the outcome?
We can point to people who have never worked on their business for more than 40 hours a week and their business has succeeded. We can point to people who have put more than 120 hours a week into their business who have failed. Who really worked harder?