It's not a common element. And because it floats, it's quickly lost to space once released.
We could technically make more with Hydrogen and nuclear fusion, or fissile products, but the price of man-made Helium would probably be about ten million fold more. It has a variety of useful properties that range from expensive to impossible to replace with other gases, namely its thermal properties, its inertness and being lighter-than-air.
Kidnapping professors just to debate them, the ultimate debatebro