I agree that part of the fun in any hobby is getting into the details and perhaps learning about the minute differences between a good cup and a great cup. But I think we differ on what a reasonable amount of money is.
Right, and for me, a premium of 20 cents per brew (and dropping) is a reasonable price to pay for 5 years (and counting) of an awesome hobby with olfactory, gustatory, and stimulant benefits on the side. So we differ on this. So what? Any further arguing boils down to differences in values and opinions over trivial matters. What's the point, to root out heretics of the One True Mustachian Way?
Frugality is a wonderful thing. So are hobbies -- even hobbies that cost money. Hobbies, or even just certain indulgences that sometimes cost money, add value to our lives in ways that vary by person. For me, not
everything is an optimization problem where the only, or even primary, constraint is minimizing cost. If you get your kicks living every aspect of your life that way, more power to you -- you'll probably be FI before most people here. I think that's awesome, but mustachianism doesn't need to be asceticism-lite in every aspect of our lives.
IMHO one great effect of Mustachianism is taking the knowledge you accumulate in a subject and using it to get your hobby satisfaction for cheap or free.
I've learned how to propagate various plants, and I've made friends with other gardeners who share cuttings and plant seeds. Have you looked at the price of plants at a garden center? My gardening hobby has become
way cheaper as I've learned more about it, and yeah, I feel pretty badass about that.
On the other hand, my coffee journey took me from a $10 Chemex type of pour-over, to a $25 Aeropress, to a ~$300 Gaggia espresso machine*. Given how much I've enjoyment I've derived from learning about, preparing, and drinking espresso, I feel pretty badass about that, too.
*For the record, I was considering the Gaggia, a Rancilio Silvia ($700), and more expensive machines with electronic temperature control. After extensive research I decided that the Gaggia was close enough in features to the Rancilio for my purposes, and that I could eventually figure out how to roll my own temperature controller with existing hardware and sensors. That's exactly what I did, and (IMO) my $300 Gaggia performs as well as a fancy $800+ machine. Not only that, but I could likely sell the Gaggia for about as much as I paid for it, due to my modifications. There's your $#%^! badassity! :D