Why are older tubes so much sought after

I wonder what will happen when all of the nos tubes are gone? and no one will have to pay the outrageous prices folks are charging for them. Will highend audio survive?
What will we do? Lord help us!
Somewhere in this scenario sanity has taken a long vacation but again, we're talking about highend audio where some would say sanity has no place.

Chadeffect, I hope you're right! but history has shown that you're probably wrong. As witnessed by the tube resurgence of the last 10-15 yrs. when obviously newer and better solidstate technologies have evolved, tube equipment is still thriving! So,obviously a lot of people still think dreadfully inefficient technology is fine.
One thing I have learned and you should've also, is that logic doesn't apply to highend audio.