Here’s the thing about helium: for many industrial applications, there is no substitute for helium. For MRI’s, there’s no substitute for helium. None. When supplies run low, operations have to cease. Period. End of story. Here’s another thing about helium: what we have on Earth is all we got. Once it’s gone, it’s gone. So that helium you suck into your lungs to make your voice high pitched? Once it’s out of your mouth, it’s gone. It can’t be used again. Here’s the third thing: there is, as of yet, no way to produce more helium. Right now in the circles studying the matter, the cheapest way to get more helium once it’s gone from Earth is to go to the Moon and mine it.

Let me repeat that: once the Earth’s helium is depleted, the cheapest way to get more helium is to get it from the Moon.

Now, let’s return to the Helium Reserves. In 1996, Congress passed the Helium Privatization Act, which directed the Secretary of the Interior to sell off the entire Helium Reserve by 2015. Of course, this was at a time when there were more uses for Helium than ever. But here’s the problem: the price that the helium is being sold at in order to deplete the reserves by 2015 is incredibly below market. It’s practically a liquidation sale. But the low prices are necessary in order to meet the Congressional directive to eliminate the helium reserve. What’s more, not only is helium being sold below market, but getting rid of the helium reserves is creating a temporary glut in supply. As a consequence, helium is too cheap. Far, far, too cheap. So there’s no incentive to recycle it (possible in industrial applications). Right now, once it’s used, it’s gone.

As a result, it’s estimated that the world could actually run out of helium in as little as 30 years. It’s because of this that the National Research Council recommended that helium reserve prices be set to market, rather than an arbitrary price, and that some reserves are kept in place. If they’re not, the NRC estimates that the United States could become a net importer of helium, a dwindling resource, within a decade. Let me remind everyone again: once the helium is gone, the cheapest way to get more is to get it from the Moon.

The easiest gas to switch to would probably be liquid

Actually, it's been proven that if you heat liquid it can turn into gas.

Um... how do you use up an element?

Or it chemically bonds and becomes unusable. We deplete oxygen (which makes up a small part of our atmospheric gases) everyday. Fortunately, other organisms, such as bacteria and plants replenish it. And humans replenish carbon dioxide along with many other organisms.

Chemical bonds don't make it unusable. They just require an impractical energy investment to make them useful again.

I always thought the point of helium in MRIs was to cool the magnets down to superconducting temperatures, I don't think liquid nitrogen is cold enough for that.

I don't think there is any major opposition to fusion power.

I'm sorry I got the terminology wrong. Does the general public know the difference? Would they both be taking place in a nuclear reactor/facility? If the answer is yes, then your clarification means nothing, because the public still doesn't trust anything having to do with nuclear facilities.