I think many of us have a passion for sound, not necessarily music and I think your interpretation of what constitute a hobby is an interesting one.
Back in the 80s I purchased the Edison mono tube amp kit x 2 from WHF. I think cost me £200 for each mono amp. I brought the kit and done some soldiering; It was a "real" hobby then and when Maplin was around I would buy speaker crossovers from them. My carpentry skills was rubbish but that didn't stop me making the speaker cabinets from MDF, no fancy dovetail joints, just glue and nails.
I think the hobby aspect of HiFi today, is experimenting with cabling, tube rolling or replacing the op-amp. Some may argue, listening to HiFi is a hobby. So easy to get pedantic but really, what matters, you get enjoyment from it.
My other hobby is PC building and customisation, much of it is standardise and modular so it's not terribly challenging today. Back when I started everything was vanilla and you had to set the pins correctly on the motherboard but like HiFi industry it has evolved.
Below, is my crazy looking PC, I added touch sensitive orb and mechanised mosquito I got from AliExpress
The desktop market has given way to laptops and the latter has given way to smart phones.
Most people don't want the fuss, want a PC get it from Currys, want a new amp get it online or from your dealership.
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