Helium is too light to stay within Earth's gravity. Nearly all helium came from underground. The problem with helium is that it's too good. It's inert, light, and doesn't conduct anything. It's really good for some specific applications, like MRIs use it.

The helium that's on Earth now is the only amount we have. The sun is full of it though, like it spits out helium by the ton every second. There's an amount of helium-3 on the moon too, underneath the top layer, and I've heard some space scientists speculate that we might eventually have to harvest helium from the moon.

It's possible to break down some radioactive elements into helium, but that takes hundreds of millions of years. It's possible to make helium-3 using nuclear fusion with tritium and lithium then capturing the decay products, but this is extremely slow, expensive, and I think less than something like 200kg of helium have ever been made this way. It's hypothetically possible to bombard deuterium atoms together to create helium. Deuterium is a hydrogen isotope that has a neutron in its nucleus. If you've ever heard of "cold fusion" that's a big part of what those people want to accomplish, reliable and efficient ways of creating helium atoms.

The cosmically ironic part about Earth running out of helium is that the universe makes helium in such large quantities that it's the second most common element. There are huge clouds of helium floating around space that are larger than our whole galaxy. Our sun builds enough helium to last us for hundreds of years and it does that in several seconds.