Moving to: m/AskMbin!

As a vinyl DJ, I'd say the Wheels of Steel: the legendary Technics SL-1200 direct drive turntable. Though they make newer ones, the vintage ones can go for a grand a piece (if it was in excellent shape) or as little as $500 a piece of they're beaten up. With servicing those things will run forever, they're the gold standard for a reason.

Snowboarding hasn't been mentioned yet.

Anyone who wants to do it somewhat seriously has their own pair of boots, from a reputable brand. Renting, or buying used boots is for rookies.

Also, there's the high-end boards from brands like Burton, Jones and Capita, which will actively try to kill anyone who doesn't know how to ride well.

As a, primarily mobile developer, my own MacBook Air (MBA) and it's the M2 version.

I do get provided with MacBook Pros (MBP) for work but there's always that advice of separating your own stuff from work stuff. And I wanted to start doing my own stuff and experimenting with beta stuff and the like without messing up the stable dev environment for work. Even though I did consider shelling out for the MBP for more power, I think I valued portability more and the MBA was just way lighter and so far, all the stuff I'm tinkering with are relatively light weight or the M2 just handles it just fine.

Also the act of switching hardware physically gives me a good separation of life/hobby from work, especially not having access to my work code and environment which gives a bit of anxiety, just like the aura of being around work doesn't make me relaxed.

For me it's my home server. 110TB at the moment, running UNRAID as a VM under proxmox. Also a load of software setup to share it's resources with my friends.

An industrial sewing machine, or an old sewing machine. It seems like every time I meet somebody who's dedicated to the craft, they're rocking some post-war anvil as an every day workhorse.

Everyone toying with system level stuff on ARM devices should have a cheap but Linux mainline capable board. Like a classic Allwinner A64 based board.

Recently I entered the world of dip pens and got a set from Deleter: Dip pen holder, G-nibs, and the Black 4 Ink. The G-nib is the most common nib used in manga drawing. It needs some pressure to do its work, but it's flexible enough to do thin and thick strokes.

They aren't hugely expensive items - the nibs can be bought in large packs for a few dollars at stationary stores, and are made to last for a few months of heavy use each. The ink is a little more expensive. It's the kind of thing where the results are better in that you can get some really sharp lines by using viscous ink that would clog anything else, but also, you'd only use it if you're deep into working with ink and aren't satisfied with felt fineliners. It's just logistically harder to deal with keeping an ink pot secure on the desk, dipping the pen, cleaning the nib, putting everything away. Fountain pens are way more popular with collectors, but dip pens are workhorses and there's almost nothing to troubleshoot, just "how do I keep ink from blobbing on it" (scrub off the protective factory coating with mild detergents or just using the ink itself) and "how do I clean it" (rinse with water).

The other tool of that type is the kolinsky sable brush - sable hair is more springy than synthetics. I am on the fence about actually getting one of those, my rubberized-felt brush pens do a decent job of getting the elements of brushes that I want, and cleaning brushes is more annoying.

I guess two sets of cards but honestly I was never big on Pinochle,

Might well be this one:
Repurposing an Accom Axial Control Panel
as it combines my previous career in TV, my lifelong interest in programming, my nostalgic tendencies, and my sheer love of buttons galore!
(Work in progress, full write-up is here.)

I don't think I have anything that's worthy of the "pinnacle" award, so I'll go with most niche & prized: a hand powered tubular key cutter, the HPC Pocket Cut-up.

It's a mini (roughly measuring tape sized) hand powered all-in-one cutter+jig that can cut tubular key blanks to any code. Any professional would probably get an electric machine instead, so I'm not really sure who needs the pocket version. The small size makes sense for someone who doesn't cut keys for a living, but the price is ~$300 usd. I found it useful for replicating the service key to my apartment laundry machine, which gives access to the hidden start cycle button which normally only presses when you pay via the coin slide. The hand cutter has standard cut depths already set so all you need to do is pick the lock with a cheap impressioning tool and measure the tool once the lock opens to retrieve the key code, which is easily translated from caliper measurements to key code via publicly available lookup tables.

At ~$300 I may have saved some money over just paying since our laundry is $5 per load and I've used the replicated key for over 5 years (back of napkin math says as long as I've done laundry more than once a month I saved money, not a high bar to clear). I could have done it much cheaper by ordering custom keys online, but being able to cut a different code in 10 minutes if I got the measurements wrong proved to be really useful.