That's about what I get after taxes, too (in EUR, ~3.6k EUR), but my retirement (with 7% interest) and healthcare costs are covered completely. Also I have about 40 vacation days and a 37h work week :)
I have multiple degrees from US schools and zero debt.
Also, most public schools will not hire teachers without a 4-year degree, so saying that those going into low-earning fields like teaching ought-not get a degree is questionable at best.
Hiring credentials is an arms race, so if everyone else is getting a degree you're going to have a bad time if you don't -- even for fiends in which no degree is logically required.
1: http://www.admissions.purdue.edu/costsandfinaid/tuitionfees....
Also: What's mentioned here: https://thehftguy.com/2017/01/23/career-advice-and-salary-ne...