I believe it's primarily the result of too many people being dependent upon corporations for their employment, rather than working for themselves as contractors or starting their own business. Working for yourself seems like a pipe dream, and if you want to impress the big companies, everyone feels like they need a PhD in theoretical physics. Plus it's become the "norm" to get a degree. First question out of most people's mouths when I meet them is, "so what are you studying for?" So now the only way to set yourself apart is to become a rocket scientist or a doctor. Or a rocket doctor. Because rockets need doctors too.