A person cannot control life and death so easily no matter how hard they may try... a person can die easily just because their body is unable to handle surgery, unable to take medication, unable to work properly or by some unknown cause. In surgery there is never an easy 100% possibility of succes.
and sometimes even a person themselves cannot control their life. Life can easily end at any possible moment or a person that wanted their life to end may survive.
life and death is a complicated matter and a greedy human with possible mental healthissues would never be able to control its course .