It's a quirky American thing. But plenty of other countries do it to. Not surprisingly it originates in sports like most of these kinds of chants. Go to an international football/soccer match sometime and let me know how many national chants you hear.

https://www.youtube.com/watch?v=FwHFm3pBA90 ("TAE HAN MIN GUK!" "Great Korean People's Country")

Here's a show giving fun lessons on how to properly do the chant https://www.youtube.com/watch?v=_Wli6OrUhNU

Here's the history of it

https://en.wikipedia.org/wiki/U-S-A!

I've heard a bunch of Brits chant something similar "UK! UK! UK! UK!" before.

Here it is in Uraguay https://www.youtube.com/watch?v=nub526rufzk

In Canada https://www.youtube.com/watch?v=KiK3f-fEDdY

In Chile, I've heard the chant is something like "CHI CHI CHI! LE LE LE! EN EL MAPA NO SE VE!", here's a comedic routine around it https://www.youtube.com/watch?v=Gigjq9GExuE

Here's the Mexican equivalent https://www.youtube.com/watch?v=s1ips57oLX0

Here's Sweden after a sports win https://www.youtube.com/watch?v=jkfqHCwB4aY

If France had a SpaceX equivalent that did something as amazing as this, it would be completely appropriate for the French people who spent years of their lives achieving something thought impossible to suddenly break out and start singing La Marseillaise or chanting.

If it happens for something as unimportant as a sporting goal, it's probably okay for it to happen for something that advances the entire species.

I'm kind of surprised by all the people from different countries that aren't even aware it happens in their own country or that they might have a similar national chant.