helium is one of the hardest substances to contain, second only to hydrogen

I think helium is harder to contain. Although hydrogen is lighter atom, it is also a larger atom due to lower nuclear charge (Z effective). Hydrogen is also a diatomic molecule, whereas helium is a single atom. I think the only thing helium has going for it is that it doesn’t easily dissolve in and embrittle metals. But helium can fit through any gap hydrogen can.