So much to unpack here. The STEM label itself is extremely misleading. There are opportunities in TE (technology and engineering) but not in SM (science and math -- well unless you get a PhD, but even then maybe not).

So people hear STEM shortage and go major in chemistry or biology and then find out there are few and poorly paid jobs so they have to accept that or get an advanced degree. Some simplification here, and individual exceptions exist of course.