There are probably individuals that have tried to store large amounts, but are going to have a sad feeling when they try to let the helium out from their million dollar bunch of tanks.
Normally you'd liquify a gas to store it, but helium doesn't liquify until you crank it down to 4°K, which is really, really cold. Liquid oxygen and nitrogen have significantly higher boiling points.
Now if you do liquify it, the real fun is it's a superfluid so it's going to crawl all over the inside of the container, it won't just stay at the bottom.
So if you don't keep it at 4°K, or -270°C, it's going to boil, and if it boils it's a gas, and if it's a gas it's going to find any opening to squeeze out of.
Not true. LHe’s boiling point (at atmospheric pressure) is 4.2K. The lambda point when it becomes a superfluid is 2.2K. So there’s a decent temperature range when it behaves as a normal liquid.
That's a pretty narrow band to operate in.
The lambda point occurs at roughly half the absolute temperature of the boiling point.
For comparison room temp is roughly 300K, and half of that is 150K or minus 120°C.
Would you call the temperature range between minus 120°C and room temp (call it 20°C) a “narrow band”?
There's also the problem of sealing the vessel it's in - since you're almost certainly keeping helium as a gas, it's going to leak through the smallest gap.
Back when blimps were a thing, the US stored a shitload of helium in a big cave. In around 2007, the US government was like "We don't need all this helium" and started selling off the reserve at super low prices.
Helium is often just vented to the atmosphere when mining natural gas, so we could capture it if we wanted, but right now it's not really worth it since we still have some cheap helium sitting around.
If you were to buy 10 billion cubic metres of helium today as a hedge on prices rising in 10 years, you may well return to find that you have significantly less in 10 years time.
The ways it's 'stored' are
a) in large [very] deep caves, which is the sort of investment an individual cannot generally make as you don't own your property to the centre of the earth.
b) in cryogenic thick walled tanks with the understanding that you will lose helium constantly, but are able to replace it with new helium. This requires a 'constant' resupply of helium, plus energy expenditure in the form of keeping it cryogenically chilled. This isn't a 'long term' storage plan, and assumes that helium prices stay low.
c) by extracting it from the ground - this is how we get helium on earth as it is, we find it in pockets alongside natural gas at reasonably great depths. This is essentially tapping into the planet's own version of method 'a'.
Method 'a' is the only real 'long term storage' we can do, and even then it leaks as long as there is some method to remove it again from the storage.