I'll chime in here with the academia perspective.
It sounds like you and I are very similar in background and interests. I, too, have a Ph.D. in a STEM field and went through some soul searching regarding academia vs high-paying job. In the end, I went with academia, earned a tenure-track position, and am a few years away from going up for tenure. I'll share my early career thoughts.
First off, you mentioned that you're a good teacher, so I assume that's your primary interest. For similar reasons, I went the selective liberal arts college route. In the event that you choose to pursue a faculty career, are you thinking R1, or liberal arts college? I ask because even in a STEM field, the pay difference between teaching and research-oriented positions can be nontrivial. If you can pursue a position in a business school with your specialization, that could be even better, but I'll assume you would be sticking to a position that reflects your engineering Ph.D.
I'll also assume that you're interested in the same path that I took, where you will be evaluated primarily on good teaching and you are free to pursue your true research interests, but it comes with a slightly lower salary. I chose this path before the MMM community was around and I assumed I would retire at the "usual" age. My mindset was that I am willing to sacrifice earning potential if it means I'll be in a field that I love and envisioned not counting the days until retirement, but rather being that old fart that refuses to retire.
Now, having discovered mustachianism and realized the possibility of retiring maybe in my 50s, I've thought a lot about whether academia was a smart move. I could have easily pursued a six figure government or private sector job and been better off financially if I chose the early retirement route. However, lately I've been feeling like I still made the right choice. If tenure is in the future and mustachian ways continue, I may find myself in the position of being able to retire in my 50s, but not wanting to since my job is awesome. I envision being in the great position of working because I like to, but being able to bail if something radical happens (new president makes faculty teach 5 courses/semester, colleague relationships go sour, college becomes too much like high school, etc.). The security of tenure, combined with mustachian ways can make a really unique career path.
These were my thoughts. Your situation may be different. I cannot tell you where your true passions lie, but I can tell you that it's okay to leave some earning potential on the table if it means doing what you love.
I can also tell you it's a difficult path at first. I am putting in 50-60 hours of work per week during the semesters. It's possible to quickly burn out in academia. I always thought of this as an easy job to half-ass, but a difficult job to do exceptionally well. If you choose to pursue a tenure-track position, you must be prepared for the following:
1) Working way more than you're paid for until you're tenured (and in your 40s, in your situation). Even then, if you're a go-getter you will still likely be working long hours as an associate or full professor.
2) A tight job market, even in STEM fields. This is a tough job to get. Even if you're a superstar teacher and have a solid research program. So do the other 15 candidates that make it to a short list.
3) Having to move to a city you never planned to. Mostly a result of item (2) above. I job-hopped twice to land in a region I really wanted.
4) The idea of the "ivory tower" being somewhat of a myth. While this is a great job, it's certainly not what most people think it is. The idea of having 3 months off during the summer is laughable (at least if you're trying to get tenure). I always tell people I get paid a 9 month salary, but really have to work on my research in the summer if I hope to keep this job that underpays me and demands 60 hours/week when I'm really "on the clock." It's really the flexibility with your hours that's the real perk, not the fabled amount of "time off." It also is pretty awesome not answering to many people, so that part of the ivory tower myth is still somewhat true.
As long as you're realistic about what a tenure-track job entails, you should be fine. In my opinion, the teaching is the best part of this job. It sounds like you would love it for the same reason.
To answer your question more specifically, the faculty path is the least effective choice if you're looking for financial independence quickly, especially in a STEM field where we tend to have much higher paying industry options. However, in my opinion, the stability and job satisfaction is worth the tradeoff. In the lower COL areas, faculty positions tend to put you at or above the median household income, anyway. You can make a good living, but retiring in your 30s like MMM is not realistic.
I can answer any other academia-related questions if you'd like. I know there are a few other professors around here that will likely chime in, too.
