There are 46 million people living in poverty in the U.S., I have a hard time believing Mustachianism can bring the majority of them out of poverty.
Eh, I don't know. People are complicated, and you can't sum up this question saying, "Look! This will work!" or, "No, not possible."
I was a poor kid, and I got out of it through a combination of education and frugality. I realized I could be different, be better, and I figured out how to do it.
Anyone who had my circumstances could do it. Thing is, not everyone had my circumstances: I was born with a healthy body, a good brain and white skin -- yeah, you can succeed without those things, but that combination does make things easier. Perhaps as important as any other detail, I realized that I could do better when I was a teen; if I'd had this same thought at age 30, perhaps once I had children, debt, or a drug-addled husband, my ability to change things would've been severely hampered.
Frugal living can help anyone get ahead. Yeah, if you're making minimum wage, you're probably not going to save anything -- I didn't save a penny in college. At that point my goal was simply to get a degree without debt. Looking back, I'm not even sure how I did it. But if a person on minimum wage can simply save $25, it's a win. If that person can stockpile some canned goods on sale, it's a win. You have to start where you are.
And poor people are no dumber than anybody else.
Again, eh, I don't know. Walk into a public high school AP math class and see who's enrolled. Dollars to doughnuts, 80% of the students in that class'll be white, middle or upper class, headed to a university. They'll be dressed nicely, driving their own cars to school, carrying their own TI-84 calculators in nice backpacks. Then walk across the hall to remedial math. You'll find the racial percentage flipped upside down. You'll see that these kids all ride the bus to "the projects", and they don't bother to carry backpacks -- they don't bother with school supplies. They use the school-provided calculators at school and have nothing at home. They get free lunch at school and two outfits of clothing and a coat from the Junior League every year. Sure, you'll find a couple middle class kids in remedial math, but they're the minority. As a group, these kids read less, travel less, are less culturally aware.
Are they dumber than other kids? Yeah, in a use-it-or-lose-it type of way. Their parents don't see much point in school -- never did them any good -- so they don't care much when their kids miss a class now and then. Could they do better? A whole lot of them could, but as teens they aren't interested in enhancing their study habits or catching up on their reading and math skills. Many of them are behind grade level.
I don't know if it's true in middle school or not, but look at the classes a student chooses to take in high school, and you can predict his socio-economic status with about 80% accuracy. Don't get me wrong -- exceptions exist. I was a poor kid, and I took AP classes. Over the years I've known poor kids who've won full ride scholarships, and I've known wealthy kids who were not academically-oriented, but they're the exception instead of the rule.