I'm a molecular biologist. I currently work in biotech R&D, although I did do a short stint in academia before ditching for the much higher salaries in the private sector.
I think Mustachianism and a scientific mentality actually mesh quite well. Science tends to be quantitative, so I'm not intimidated by math or numbers, and will happily bust out with spreadsheets and graphs to model/track FIRE progress. I value a rational, pragmatic, evidence-based approach over emotion-based decision-making, so I can smell bullshit from a mile away and more easily resist the lure of slick advertisements for useless crap I don't need. I love optimizing, experimentation, and problem-solving, so I enjoy figuring out the best and most efficient way to accomplish a task. The education helps, too -- I'm quite willing to get down into the weeds and read the proper (and not just the popular) literature on topics relevant to financial planning and management.
You do make an interesting point regarding the PhD, though. I distinctly recall the surprise I felt when I read in The Millionaire Next Door that while advanced degrees were positively correlated with income, they were negatively correlated with wealth. (The relevant quote is, "For all high-income earners (those earning at least $100,000 annually), the relationship between education and wealth accumulation is *negative*. High-income PAWs are significantly *less* likely than UAWs to hold graduate degrees, law degrees, or medical degrees" p. 74.)
I was strongly considering getting a PhD at the time, and reading that actually factored into my final decision (along with external factors beyond my control, such as my PI losing funding for my position) to delay grad school and pursue a more lucrative career in industry. I figured that if I sold out, I could use my higher salary to front-load my retirement accounts, after which I could pursue grad school with the peace of mind of knowing that my retirement will be fully funded by the magic that is compounding interest.
As it turned out, after jumping ship to industry, I was never able to subsequently justify the opportunity cost of giving up that decent salary and livelihood for the drudgery and indentured servitude that is grad school. I also noticed that, at least in industry, non-PhDs have greater career flexibility than those holding PhDs (this is not the case in academia). At first, I held off because my employer was paying for my Master's, but now I'm quite glad I didn't go for the PhD, because after discovering last year that FIRE is a thing, I realize now that the fastest path to it is exactly what I've been doing -- banking as much change as possible as early as possible. Six years would have been a LOT of time to lose when I can achieve FI without the PhD in twelve or so years.
I do think that science is a career of passion rather than of expedience, though. People don't really go into that field for the money or because they accidentally fell into it somehow. I genuinely enjoy and take pride in my work, and I'm actually struggling a bit internally over actually pulling the plug with FIRE when we reach goal. But we'll cross that bridge when we come to it.