A friend was pitching me a stock last week, genuinely lit up. They are doubling their factories, buying a smaller rival, raising fresh money to pay for all of it. Fast growth, fast returns, he figured. Sounded obvious. So I pulled the research that has tested exactly that on every US stock since 1968. The companies that expanded the hardest went on to be the worst performers. The boring, slow growers quietly beat them. Not by a little.