[OrsonSmelles]

While I've said something like this comment scores of times in my life, and it's definitely a necessary corrective for a lot of optimists who don't think too hard about how they think, I don't think it's a useful place to stop. It's not hard to get unanimous agreement with "be a realist!" because it's framed so the alternative is irrationality/delusion. But even among people who agree that the goal should be to reason under uncertainty and assess risks clearly, there will be a spectrum of risk tolerance, and I don't think it's the worst thing ever to describe that as "optimism" vs. "pessimism"! (I fully acknowledge this isn't the dominant usage, but I think some spaces lean this way)

In this context, I tend to read the parent claim as something like, "great success requires willingness to sometimes take worse-than-even odds or pursue modestly-negative-EV opportunities". I'm not sure I agree with the strongest version of that, but I think it's likely that the space of risky paths to great achievement is richer than that of cautious ones.