It's important to factor in opportunity cost *and* compare the trades to all degrees. Most degrees are worthless and represent a massive opportunity cost (+4 years of foregone wages + debt multiplied by an average 8% ROI if someone just stuck that cash in a S&P 500 Index). You're spot on that in the long term, high paying degrees in STEM out-perform the trades both financially and physically. However the majority of degrees are a negative ROI however you slice it.