> Imagine if instead of harvesting helium directly we find an economic way to split nitrogen (somehow, who knows).
This is nonsense, from the physics point of view.
The reason why rubber/fertilizer were replaced by oil/gas products is that
oil/gas has the energy needed for the (relatively simple) chemical transformations needed to obtain rubber/fertilizer from the feedstocks.
Splitting nitrogen into helium is a nuclear reaction that requires copious amounts of energy.
At least using fusion or collecting helium from Moon/Jupiter are physically sane, if economically insane.
This is nonsense, from the physics point of view.
The reason why rubber/fertilizer were replaced by oil/gas products is that oil/gas has the energy needed for the (relatively simple) chemical transformations needed to obtain rubber/fertilizer from the feedstocks.
Splitting nitrogen into helium is a nuclear reaction that requires copious amounts of energy.
At least using fusion or collecting helium from Moon/Jupiter are physically sane, if economically insane.