To avoid accidents, that is why you must know where you are and who is flying next to you. This guy just wanted to entertain his friends and chose to do a final loop with his hang glider before landing. As you can see, it was a big mistake. He crashed into a paraglider and lost control of his own glider, did a nose dive towards the planet and hit ground fast and all this happened in front of his friends. Yup, that really hurt.