Updated Aug 9
Minimalism is about simplicity, and black is a simple colour.
Black is unobtrusive, barely noticed. Nobody is distracted by your plain black shirt, or the fact that you always wear identical plain black shirts (compared to something bright, or patterned).
When you only have a small amount of clothes, you don’t need a reason to choose black. Because it is simple and classic, for all socioeconomic situations.
When all of your clothes are the same colour, then you don’t waste time choosing or thinking in the morning. You don’t waste mental energy about whether a certain outfit looks good today. I could easily get dressed in total darkness.
I am privileged to be spending my days in a relatively informal environment, where brain-power is more important than attractiveness.
My current “uniform” is $8 stretch jeans, one size too large (because I like being comfortable), from K-Mart, plus either a plain black T-shirt, or turtleneck, or fleece sweatshirt, depending on temperature. Plus whatever cheap comfortable shoes I get every few months, from a chain store.
Underwear and socks are cheap, plain black. Nobody sees those, anyway.
In the past, I have had some bizarre encounters with people who accused me of trying to make some kind of “statement” with my clothing. As if I were morally obligated to be constantly thinking about random strangers, and their opinions on this.
As long as my clothes are clean and in good condition, nobody as any legitimate reason to care.