If Trump has nothing to fear then just let the investigation work itself out. Then if nothing comes out of this he has the ultimate "I told you so" coming to him. In my eyes Donald Trump won the election over Hillary Clinton. And he is the POTUS. This investigation is because of a foreign government's possible influence in the election. If Trump is not worried one bit then just settle down and wait for the outcome. What bothers him the most is Mueller has the power to look everywhere he wants. This is what Trump is scared about the most.