The two-phase structure
Phase one plays like a normal tournament: no bounties are awarded and survival is the only objective. Once the field reaches the announced threshold, phase two begins and every elimination awards a randomly drawn bounty from the pool.
Because the bounty pool is fixed and distributed unevenly, most draws are small and a few are very large. That distribution is the entire strategic point: the expected value of an elimination is the average draw, not the top prize people picture.