You have to take into account, that you start to earn money from a very young age. And you don't start your career with huge student debt. Skilled workers have a huge head start and it's easy to find need jobs because of the demand. If you're smart and good at your job, you can create a decent life for yourself with skilled labor. Especially because all the smart kids seem to do the "smart" thing and go to college, leaving more demand for good laborers in the skilled labor market.