Earlier quoted context omitted.
> Just make the damn thing require an internet connection all the time. I don't care. Not everyone has perfectly reliable access to the internet.
Most people who can download a 50GB game tend to at least be able to have a connection that allows the game to phone home once a minute or so.
Maybe that person went to a place where they could get Internet, downloaded the game to a suitable storage medium and dragged it over from there into their steam folder at home.