>>1607157$700 isn't that much to spend on a bicycle. It gets you a decent entry level hybrid new.
Does it make more, or less sense to do a 'custom' build on a nice old chromoly frame? Depends on if you like wrenching really.
And lets say someone strips off a nice functional 3x7 or whatever drivetrain from their bike, to put on the latest 1x10 meme. It's a total waste of money, and often it ruins the charm of those old bikes, but it's not like you're throwing away the old parts, or wasting time. They can be used on something else one day. And a nice old bike warrants being completely stripped to be rebuilt anyway, regardless of if you do a 'build' with gratuitous new parts or clean the old ones and restore it relatively stock. It's not like you should just 'leave it alone' either way (you can, but overhauls make sense). The key part is servicing all the bearings which you'd hopefully do either way. Someone 'just riding it stock' is more often than not riding it into the ground.
Restoring old bicycles for use is basically peak anti-consumerism.
