The short answer is that the "we're running out of helium" scare stories have always been grossly misleading, for much the same reasons that we've been hitting

The short answer is that the "we're running out of helium" scare stories have always been grossly misleading, for much the same reasons that we've been hitting "peak oil" for two decades now. Helium is available, as this story makes clear. But there's been enough of it recovered from mining & gas extraction that it hasn't been profitable to do direct helium-only exploration; this is also why it's cheap enough to use on birthday parties. As the helium reserve declines, and known helium sources dry up, prices will rise (are rising). That will drive an increased market for helium exploration. Presumably demand for balloons is much more elastic than demand for medical helium, so I think the answer is "we aren't that short on helium yet".