It's not widely considered due to how the second half of WW1 ended up going, but Germany really wasn't the bad guys in WW1. It was like every other war except WW2, both sides were kinda shit and kinda okay. And given that fact, it was clearly a mistake to let the victors write the treaty of Versailles to be so harsh, while the losers were still a quite formidable force. Though as a 21st century person, it's hard to say how many of the German complaints about it were legitimate vs how many were an excuse to be fascists.