I'm not informed on customer demographic differences between Costco and Walmart, but I'd think that a poor economy will disproportionately affect Walmart due to economically disadvantaged people won't be shopping at Costco in the first place and they tend to be the ones hurt the most in economic downturns. So "better" customers could be leading to better financials on the part of Costco, not just some anti MBA culture that resonates with the HN crowd.