Small historical point
The Hindenburg was actually designed to use helium, but the USA, which has a virtual monopoly on the supply, refused to supply it to Germany, despite the fact that it has no strategic value and that, in any case, as the Hindenburg lost ~5% on every trip across the Atlantic, anytime the USA had wanted it could have cut off the supply.
Also worth pointing out that the Hindenburg and its predecessor, the Graf Zeppelin, provided a regularly (weekly?) service between Germany and Brazil.
Until the disaster not a single passenger had been harmed.
Had the helium been available...