The National Helium Reserve was started in the 1920s to store helium for military airships and barrage balloons; but airplane technology got a lot better and so we don’t use airships or even many balloons for military purposes anymore. So the original purpose of the reserve never turned out to be all that useful.

Helium is found alongside natural gas, and there is still plenty of helium production in the US. Until we get a real room-temperature superconductor, every MRI machine consumes liquid helium for cooling. This and other industrial uses make it profitable for natural gas producers to keep extracting helium.