If you care about ethical production it's difficult to spend less.
> "Albert Einstein reportedly bought several variations of the same grey suit so that he wouldn't have to waste time deciding what to wear each morning."
This sounds incredibly joyless -- the aesthetic equivalent of eating huel for every meal.
Joyless for some, bliss for others.
Is it a requirement of ethical production that clothes don't last and must be regularly replaced??
You may like clothing, playing with what you wear may give you joy, but for some having to find clothes they feel comfortable wearing, then having each day to select something to wear, ensuring that they meet some criteria that will avoid negative perception from their community is nothing short of hell.
When I find something that fits well, is comfortable and reasonably inexpensive, I purchase a bunch of them and wear them daily for the next couple of years.
That depends on how you derive joy from it. My wardrobe is fully interchangeable and I generally pick what I wear at random. It's all carefully selected to be a reflection of my personal taste. Having a personal uniform makes me quite happy.
Personally I don't think it's zero sum, enjoying your meals won't make your immaterial pursuits less worthy, for example.