I'm guessing the point is to avoid the rookie mistake of saying something like: "The total market in X is $Y billion, and if we only get Z percent market share

I'm guessing the point is to avoid the rookie mistake of saying something like: "The total market in X is $Y billion, and if we only get Z percent market share, we will be a great success." The hard part is to get that first net dollar of profit in a market, not to dream about some fraction of the entire ocean. Do investors take special training to avoid rolling their eyes when entrepreneurs give them the "only X percent of the market" line?