1) Go to: https://www.epicgames.com/account/connections and disconnect Dead Island 2 from the "Apps" section.

2) Start the game from Steam and once in the game, if you're prompted to connect Dead Island 2 to Epic, decline, and voilà, you won't be stuck in the endless loading loop anymore.

Additional Info


I know that this method still won't allow you to connect and play with your friends from Epic Games, but at least you won't have to modify files, and having EOS installed will suffice. For now, this is the only solution that also includes enabling the achievement system. Until the double loop issue of the game requesting connection to the app and then conflicting is resolved, this is the only way without modifying any files and without giving up Steam achievements.