You guys have to realize he didn't make everything you see in the game, and I bet you he didn't make the swimming animations either. Look up Quixel MegaScans, he didnt model or create the high quality textures for the forest, the cabin and a lot of other things. He definitely did for boots or bed or the unique stuff, but Unreal Engine users get the entire library of Quixel MeganScans for FREE. There are also a massive amount of free and paid animation packs, Adobe Mixamo being the best example with thousands of animations. Those are all free to use, and I bet you the swimming is probably there or from another pack.
He does way less work than you guys think. People put together forests, cabins, entire maps in UE4 in a few hours if you check youtube. Ultimately he's the only one willing to do this kind of work though and the character models are really high quality in the end, so he wins.