Reverse Hunger games.
Every year, we reap 10 of the 100 wealthiest people to fight to the death. The odds of being chosen are proportional to their net wealth; they can surrender wealth to lower their odds.
The chosen have one week to prepare. If you can afford a giant killer robot, now's the time.
The losers' fortunes are donated to the poorest countries. The winner gets launched into space. If they did very well, they're inside the rocket instead of strapped to it.