I was a business major in college, but not a good one.

Once, a classmate off-handedly explained a decision he'd made with the rationale that he "knew what his time was worth." I was speechless.  How did he know?  And what was it worth?  This guy was cranking away at a couple businesses halfway through undergrad.  His older brother once described him as seeing the world in "green and white."  Still, he knew something important then, and I suspect he's capitalized on that knowledge for a long time.

My guess is that 99% of us undervalue our time in dollar terms, mostly because we never do calculations like this one.