An extra note: An undergrad degree in econ can be very useful in getting familiar with the terminology and the sorts of facets that finance and economics professions are interested in. Beyond the BA/BS in Econ, there isn't much more to learn in post-graduate economics. My suggestion for anyone wanting to learn economics is to learn it in undergrad and mix it with another discipline.
I am surprised Abnormal Returns picked up this link.
I majored CS and with minors in Math and Econ. The economics minor was one of the better decisions I made in college and sometimes I think I use it more than the CS stuff. For example, things like opportunity cost I use almost every day, while it's rare I analyze the "big O" run time of code I'm writing.
From what I saw of the higher level econ classes, you're completely correct. For the most part they're not learning much new stuff, they're learning the same stuff in more detail and investigating why. It's interesting, but has limited applicability to real life. The low level courses are also interesting but have real life applications all over the place.
A good undergrad minor will certainly give you the more readily transferable skills: a grounding in econometric/statistical techniques you might actually use, a style of reasoning that covers things like optimal pricing and game theory and an overview of what the main economic debates of the twentieth century were and their policy implications. But if you like a challenge the PhD is generally regarded as an order of magnitude harder than undergrad economics, more so than in other social sciences.
I'd recommend instead learning this stuff through Coursera or CFA or actuarial exams instead. Way cheaper and there's no benefit to the classroom for this material.
I looked at an actuarial textbook once, and almost all the material seemed so specialized that I don't see why anyone would recommend learning it unless they were actually going to be doing actuarial stuff.
A popular actuarial textbook like "Actuarial Mathematics" is extremely specialized (especially to life insurance) and would only relate to the 3rd exam (MLC) and beyond. However, the first two exams are much more generic to statistics and finance respectively.
I am surprised Abnormal Returns picked up this link.