The value of a lot of things in life including an engineering degree cannot simply be reduced to a dollar amount, unless the moment you set out to get a degree, your only and final goal was how much that degree would fetch you down the line.
Unfortunately that isn't really up to us, since in our society you have to work to survive until you die or retire. Until having no job means a livable lifestyle, most people have to consider real dollar values when considering education.
Well then, we'd better get to work on fixing that problem, shouldn't we?