ufc [#5]
you will never lose everything, athletes do not rely solely on playing tournaments, just like actors don't simply rely on roles in movies (might not be the best comparision), they will always have a business that they invest in, they can always be coach or use their experience in a different field as a consultant
Obviously you have to have financial security, but athletes need to invest in that on their own. Unlike other jobs where you have a position on your own without actively competing with anyone else, sports relies on intensity and uncertainty for that financial breakthrough. Most jobs arent fully secure, and a lot of people with the money will invest to grow their capital passively, but just saying your own position within a league can become obsolete with a few bad performances.