As it turns out, helium (and hydrogen) will escape Earth's atmosphere, so there's not a whole lot up there either. Here's a great Quora post on the escape proc

As it turns out, helium (and hydrogen) will escape Earth's atmosphere, so there's not a whole lot up there either. Here's a great Quora post on the escape process: https://www.quora.com/What-makes-hydrogen-and-helium-and-atoms-alike-flee-the-Earths-atmosphere-and-not-be-bound-by-gravity-sufficiently-to-stay-down https://www.quora.com/What-makes-hydrogen-and-helium-and-ato...