I wanted to look at some of the things many mustachians do on the penny pinching side while they still make the huge mistake of paying down a mortgage early.
You're relying on a flawed (and kind of condescending) premise. For many people, paying off a mortgage early instead of investing that money in something more remunerative isn't a mistake at all – it's an opportunity to free themselves from the grind sooner.
I know that in your "the math works out better" world, that doesn't make much sense. Bear with me. As hard as it is to believe, a lot of us have thought this thing through and decided to annihilate the mortgage anyway. Ahem...
It is true that you will get richer by investing in an asset that returns 6% over a long enough time horizon than by using the same money to pay down a mortgage with a 3.5% interest rate. Nobody disputes that.
But paying down the mortgage early can also lower one's expenses dramatically, which allows many people to:
1. Quit a job they hate and transition into part-time work that they love in just a few years instead of several years
2. Start a business, spend more time with their kids, learn a new skill, socialize more, and see more of the world SOONER since than they would otherwise ('cuz they don't need that full-time job anymore)
3. Start doing a lot of the stuff that they want to do post-FIRE right away while they're younger and healthier. You're more likely to live 5 more years than 10 more years, you know?
These benefits are even more significant for self-employed people, who can more easily (and quickly) reduce their client load and exert more control over their lives after they no longer have to dish out, say... 1.5-2K per month on a mortgage.
As someone who would prefer to optimize his time sooner rather than later, I'll be paying off my mortgage early. I know I'm missing out on seeing a higher number next to my name in the "net worth" column. Meh. All else being equal, you're gonna get richer faster than I will.
But while you're still hacking away at your full-time job, I'll be fucking around on my bike, jamming on my guitar, having that extra beer, and reading that book you didn't have time to pick up. I'll also do some fun part-time work to keep the bills paid and pad the Vanguard account, but I won't have to say no when a buddy suggests we leave for a backpacking trip on a Wednesday.
You might think that's a "huge mistake," but I don't.