I think there are many paths to becoming a millionaire, and he is telling lessons he learned. I've also known other people who have lived abroad and were able to save more money, especially if that person or spouse also can earn in that country doubling your earning power. for some people, owning a home makes financial sense, especially if move rarely or never. In other situations renting is better. I think the tenets of minimalism help in whatever situation you are in.
I definitely made a similar mistake to him, in that I'm "over educated". While I accrued no loans, I was in graduate school and in a post doc during what could have been prime earning years. My job does use my degree, but I don't need my degree to do my job. Hindsight is 50/50 so I'm not going to beat myself up, but just work on going forward.
Myself one of the things I toy with, is moving. I can afford the mortgage, and it is set to be paid off in 8 years. I love my location (very walkable) and I can see retiring here. However, my house has accrued in value and due to divorce an even large percentage of my net worth. It's possible for me to get a similar house in a less walkable area, pay off house and pocket an additional 50+K. So it's something I toy with. I haven't come across another house that to me tips the cost/benefit ratio, but who knows.