Because Trump has alienated everybody including his allies all around the world. So now US has no friends and is fighting alone with China. US and China are like two sumo wrestlers fighting in a ring with the whole world as spectators and making money off the side from the fight. Neither US nor China is going to come out on top from this trade war but the true winners from this war are going to be the "alternative economy" countries, continents, and organizations like Vietnam and India and even Africa who are the alternative cheap labour to China and EU and to a smaller extent Japan who are the alternative to US.
No, not really. It's because the EU has a $49B trade deficit with China - not a $470B trade deficit.