There are a lot of off ramps to comfort on the road to greatness. The hypothetical man who is genetically sufficient for the job (a short man will not succeed in many sports nor will a man with a bad voice be a good singer, a creative mind will not excel at the analytical and an analytical mind will not succeed at the creative), and mentally "just gets" the volumes of understanding it takes to be a once in a generation performer of some craft by mid teens or so will in starting down that path will necessarily achieve the intelligence to determine that there are other, orders of magnitude more sure paths to a comfortable life.