Big Bang Theory had the girls do a great hilarious deconstruction of "Raiders of the Lost Ark" ruining the movie for the guys: Indy doesn't really accomplish anything positive other than killing some bad guys. It is his fault the Germans get their hands on the Ark because they were digging in the wrong place. If he gave up or failed then, it might have been taken to Berlin and opened there, killing Hitler and ending WWII several years earlier. Instead, it gets opened in the desert. And, it doesn't end up in a museum but a warehouse.
But the Germans were only digging in the wrong place because Indy got the headpiece from Marian, leaving them only half. If he hadn't, they would have gotten it and been digging in the right place all along. Which I think BB mentioned. Would Belloq have delivered it to Hitler or opened it himself as he did in the movie?