I don't know if I'd go so far as to call it "manchild" territory: hobbies are fine, and if your hobby is DIY mechanical keyboards, more power to you.

Where I start to break out the scepticism is when people start talking about how much more productive they are because of their fancy keyboard, or how important exactly the right keyboard is to productivity.

That's mostly nonsense.

I've got valuable work done in a whole variety of more and less ideal/noisy/comfortable/uncomfortable environments on a 13 inch laptop using its built-in keyboard.

The primary driver that makes you productive or non-productive is your motivation. If you want to get it done you'll get it done. To a very large extent, everything else is incremental. Multiple monitors, fancy keyboard, cool mouse, ergonomic chair, whatever. They're nice, and they do help a bit. But, fundamentally, what really gets things over the line is desire, motivation.

Whereas a lot of this work adjacent stuff is a form of procrastination.

I've gone through a similar experience with musical instruments and studio gear, versus actual music creation. At some point you just have to stop tinkering and start making music, and what I've realised is that the only item I have available to me at almost all times to do that is my laptop, so maybe I should focus on working in the box instead of on acquiring more hardware.

I really hated most keyboards but had realized that some keyboards were better than others: for example in the nineties I had an amazing keyboard on a Mac. Then I worked on IBM Model M a tiny bit (big mainframe terminals).

So I started looking for both a shape and a switch that'd suit me. I obsessed over it.

I even got a few collectible ones: a very rare split Cherry MX-5000 keyboard (comes stock with cherry brown switches but they could be swapped) and then the rare real "industrial" IBM Model M (in olive grey instead of beige color).

Eventually I found out Topre switches on the japanese HHKB keyboars (Happy Hacking Keyboard) and as I've got family in Japan, I had three HHKB Pro JP shipped to me (when family would come to visit).

I don't speak/type japanese but I dig that japanese version as a very narrow spacebar and hence more modifiers and modifiers that are easier to reach with the thumbs.

Been a happy camper since more than 10 years now.

So basically... Maybe I obsessed over it a bit but then I eventually "found" my keyboard and it's the HHKB Pro JP and found my switch: and my switch is Topre and nothing else.