Where are the young audiophiles?

I think this is far from true. There's a big resurgence in hi-fi here in Los Angeles. Bars like Gold Line and In Sheep's Clothing are reinvigorating the interest, plus brands like Common Wave and Ojas have huge followings with high-end designers and lots of young clientele. I think these communities are skewing toward vintage and the Japanese/Kissa vibe, and less toward the "hi-tech", brutish systems of the 90s/early-2000s.

I work at a record label and we're selling more vinyl than ever. The plants are totally bottlenecked due to the covid surge, which I think is being driven by people under 40.

We're also not lingering in forums that disparage entire genres of music, lol. Maybe Millenials and Gen Z have realized that life is too short to bicker on forums.

Most brick and mortar audio stores over last 12 months are doing much better than they've done in years.  I don't buy that clientele all old.  I see younger people in the stores.  Nice headphones are in demand and that's a gateway.  Things are fine 

Headphones are extremely hot these days. They guys into that are as crazy as the folks here. Likely the gateway drug to a home system once these folks get established in career and home.

The worm will turn

A lot of it comes down to expendable income---older audiophiles have the income to buy more expensive equipment than the younger folks. Plus stereo equipment back then was not as expensive as it is nowadays. Some of the younger audiophiles I follow on YouTube are into headphones and smaller headphone amps. Some of my younger friends are getting into vinyl but they're not into 'fancy' stereos (yet)---they get their enjoyment out playing the records. I just posted something similar to this a few days ago.