I agree with much of this, but I do think that there is a flaw in his logic - he operates on the notion that saving more of your income has a two-fold impact on your ability to retire.
First, and most obvious, it increases how much savings you have. But secondly, he states that you permanently decrease your expenses, making that magical 4% withdrawal rate of your savings easier to attain.
And yes, while that is true on the surface, the underlying message is - if you just don’t have cable tv (streaming in today’s world) and other things like cars and basic vacations, then you are almost there! And yes, if you want to live as a monk then this could be considered by some as a noble thing. But some want to live reasonably comfortably (new-ish car, trips to places like disney world with the kids while staying in a nice hotel vs biking and camping).
I only bring this up because even mister money mustache has admitted that he is unusually monk-ish in his lifestyle choices. Don’t get me wrong, I actually retired 7 years ago partly on reading his blog, so I get it. But we have to be realistic on what his message is and what others are liable to achieve.
I guess what I take most umbrage with is, he says that it is easier and more effective to cut expenses than raise earnings. And just like a business, this strategy quickly runs into diminishing returns. Raising the top line while keeping expenses reasonable is always the best strategy to an early retirement (or a successful business).