Point taken, yet while the margin of failure may be smaller for becoming a medical doctor, it still has an effect on how great the success for it is. There's obviously other factors involved, like the fact that succeeding in becoming a medical doctor will most likely help you succeed in life (depending on what your goal in life is). I guess you can't say, "The larger the margin for failure, the greater the success," but what you can still say is, "Success is nothing without failure," as no matter what, the margin for failure will still effect how great the success is.