I should've phrased my reply better what I'm saying if you are skillful enough to make a game of this quality which demonstrate they know their way around Unreal, there is no way they're backing up "everything", but most likely just backing up their code and project files without all the art and 3d assets because that is a level of redundancy that just wouldn't make sense even to a new game maker after a few USB sticks.

First game I worked on for publishing I did it on an airgapped pc and my version control was indeed backing up the project between every major change (and in between) with hand written and notepad change logs so I don't get lost. Putting my baby on the cloud so some google employee can see my brilliant game and steal my ideas? No fucking chance!

Now? fuck, I'd script on vscode dot dev if I had to, I don't give a shit, no one is gonna steal my shitty ideas haha.