Lots of businesses make less than stock market index returns. You can be a builder that doesn't want to beat the S&P and still support your family doing it. Not everything has to be about massive accumulation of wealth or "growth at all costs". Plenty of people are OK doing a day's work for a day's creature comforts and leaving it at that.
Sure you can deliberately invest in a way that doesn't generate the best returns. You can be a philanthropist and build housing for free! But the vast majority of people are indeed looking to maximize returns.
