Which is the problem with your presented stat. "People with degrees make 40% more over their lifetimes on average" is useless because it tells us nothing about whether it's worth the capital expenditure. Just making more money isn't the point, having a better life is the point.
So it is very relevant, and your statement here is basically an admission that your 40% stat I keep seeing in these threads is equally irrelevant. "You can make more money and still be burdened" equates to "making more money won't necessarily make your life better." If that's true, what the hell is the point of going to college? To make 40% more?