I have one very mustachian friend. When I learned about the FIRE concept, I told him about it. He responded that it was an interesting thought. A few years later, he and his wife bought a clown apartment at twice the price of our former clown house. They even had to take up a mortgage. I guess he won't be retiring amy time soon. When we visited him, I didn't remind him of the FIRE concept. But he is still being mustachian otherwise. They don't own a car and both cycle to work. And just like us, he likes to spend his summer vacations in a tent.
We have other friends of whom one is a mustachian, because he grew up with parents who had to watch every penny. But maybe because of that, he is also a hoarder. Old, non-working vacuum machines are to be kept, because one day he might repair them. By now, they have 3 non-working vaccuums that are still not repaired. The couple drive a sensibly priced car and live in a sensibly priced modest home. But they do own a cabin (with a very old locally stored monster truck), a shared-with-siblings holiday home (former parental home) and a sailboat. I think all these things in total are quite pricy. The man is already retired, taking up early pension in the tradional system, at 62 or so. His SO is much younger and as far as I know still has a study loan. I don't think early retirement is an option for her. She is sometimes into not being stuff or clothes for a year. But I don't think she is that much into saving as her SO.
My other friends might not be mustachian, but I meet them on trips in the forest or other cheap activities. Once a friend invited me to fly a weekend to New York for clothes shopping. I declined, mostly because of environmental reasons. And because I thought it would be an outrageous spend. But we can still meet otherwise. Her SO makes some of his own clothes.
I also have quite a few aquaintances through my mushroom club, who all forage their own food. When we go on a trip with the club, we eat our packed lunches in the forest. But during the yearly meeting at a hotel, I am usually the only one sleeping at a campsite or in a hammock in the forest. The rest will pay the high hotel prices.