Part of the reason there's a shortage is because the US was the main supplier. There was no market incentive for anyone to invest into helium extraction.
It'd be like if the US used it's strategic oil reserve to supply the US with oil at a low price at all times.
A strategic reserve isn't supposed to be used as a supply. The existence of a strategic reserve shouldn't have an effect on the supply of helium except in an emergency. The fact that selling the helium reserve could create a shortage should tell you that it wasn't being used as a reserve but as a supply.
The US was, essentially, artificial subsidizing the price of helium. What's happening now is that people are actually paying the real price of helium.
Exactly right. We may yet find out what happens when someone sells the strategic oil reserve.
The US government decided (maybe correctly, IDK) some years ago that their strategic helium reserves were too high (and thus expensive).
There were several announcements, a lot of discussion, and a long process before they started selling it. It was also a temporary action, with a well known end-date (that TBH, I never looked at). It had a known and constant small pressure over investments, it wasn't something that destabilized a market.