I hear this pride in having few 'things' from some folks - but it seems like it frequently comes from people who aren't creative, enjoy making things, or have non-computer related hobbies.
If I have items which only do one job and another which covers several, the single-use items go. Eg: I only have gas for heat, so a kettle would be heated on the flame. But it can only heat water, whereas I have a saucepan which can heat water and also heat other things. So I don't need a kettle which I'd have to find space for when other things are on the hob (I really am in a small space). The same thinking has been applied to tools.
I paint a lot so throwing away paint and brushes would be wasteful - I'd end up buying more. But I also had lots of gathered/found materials which I use for recycled art - they got chucked (sad but they were rubbish when I collected them). When I want to do some recycled art I'll use what I can find at the time. The paint/brushes etc. that I kept live in a simple wooden chest. Its flat top is extra worktop space when I need it (eg. putting down a hot pan). Put a cushion on it and it's a seat. The table I paint at folds down to become my bed at night. I can't paint quite as large as I used to - fine, this will be a different phase in my life as an artist. I can't store loads of canvases but it's ok I just have to act more responsively. A good artist can make art with pen and paper, I learned to embrace restrictions as part of the creative process years ago.
I'm a long way from 'all fits in a suitcase' but I've got down to maybe 10-20% of what I owned a year ago. I feel lighter, more efficient (stuff's easier to find!), more free to relocate to different kinds of living spaces. I've shed a lot of nostalgic attachment to objects which I thought were important but do not miss.
It doesn't have to be all or nothing. I refactored :)
Elsewhere in my life, I don't have a lot - I think I only have two drawers full of clothing and perhaps a few books and stuff. I have considered downsizing, but pretty much cannot bring myself to give away so much stuff that brings me joy.
My wife is the same - she is an artist, and has two separate areas of the house set up as her studio. Each is filled with canvases, paint tubes, easels, wooden boards, and a myriad of other stuff she uses for her mixed media work. Without any of that, I don't think she would feel as fulfilled and engaged with life, nor have a conduit to de-stress from every day responsibilities.
Tools (lots of them), art, and furniture (we buy mid-century designer).
Everything else is trash. Why do we keep trash? Why do we buy trash?
Because the sad simple truth is that buying trash, using it until it breaks and then buying a new one often makes more financial sense than trying to buy quality.
12 years ago I bought the best quality TV I could afford. And while it still works perfectly, it's objectively worse in just about every way then a current TV costing 20% of what I paid for it. However since it was so expensive and still works I cannot really bring myself to replace it.
For many of those, I would build up and hold on to things because I thought they'd be valuable some day, or maybe future kids/grandkids would benefit from having something handed down. I also like history and really enjoy seeing antique craftsmanship.
Even though stuff like the Beanie Baby craze crested and fell pretty quickly, you still have shows like Antiques Roadshow and Pawn Stars that show all of those hidden gems. Or, in the coin world, you'd read about some trove of uncirculated buffalo nickels being discovered in an attic somewhere. Or, if you ever go to the Andy Warhol museum, there's a whole section dedicated to his "time capsules" of collected mundane stuff, much of which ends up providing some kind of historical value.
When I was a kid, no one told me about putting money into mutual funds and compound interest (or if they did I didn't listen), let alone the principle of survivorship bias. Besides, that stuff is boring compared to the Star Wars Episode I Pez collection and commemorative Pepsi cans[1]. If I had held on to my 20 our of 24 opened cans, maybe I could have sold them for 30 bucks or so!
I've been having a lot of reality checks as I get older. I kept my Star Wars prequel novelizations in good condition, but I can also get a book in similar condition on Amazon for 5 or 6 bucks. And I never read my parents' favorite fiction books, so there's a solid chance that my kids won't care either. Maybe in the midst of getting rid of these things I'll get rid of the one thing that could be worth thousands in a generation or two, but that's like playing the lottery, isn't it?
[1]: www.ebay.com/itm/Star-Wars-Episode-1-Exclusive-Pepsi-Display-Collectors-Item-Set-of-24-Cans-/253064909025
Then, as programming became more and more of a 'day job' and not a fun side project, I found myself getting rid of the clutter of obsolete equipment around the place. 35 years later, I am happy with just a basic iMac as my main development machine, and a Lenovo laptop as my Windows/backup development machine. That is it. No more multi screen setups or fancy keyboards & mice even - just stock standard stuff to get the job done so I can spend energy on my passion projects.