One thing you can do with the old stuff that isn't remotely possible with new is put together fine rides for small sums of money. My latest is a ~40 yo Reynolds 531 frame purchased for $80 with s $30 FW, say $20 in derailleurs and shifters, $35 in brakes. The ride? Like a racing bike of many years ago, designed to reign supreme on rough roads, with or without pavement.

Yeah, I could get a Surley, 9-10 speed cassette and wheels, etc and get to about the same place for only about $800. (And have a desirable, hi-theft item). Nobody will notice my beat up frame.)

I don't do old just because it is old. But good doesn't get old. It stays good. And good bikes have been made for over a century.

Ben