I only have two theories...
Either a big surge of people can't wait for the next game and wanted a new go at GT (can happen near next release, but I'm not sure it's the case here?)
Or just one buyer got hacked or is a bot, and they put the download link on some shady sites? Idk how they could manage to give the data here, but heh..
Other questions, are the demo and full game data separated? Cos could also be bots downloading demo in mass for whatever reason