Slippery slope. How do you confirm that the doctor was indeed killing him because he asked or if he was doing it cut hes insane, or monetarily motivated.
Then what if the patient isn't in the right state of mind. My god, what would the life insurance companies say about the entire idea.
Actually, very unslippery slope.
All you need is a competent witness to sign off on it, that works with wills anyways.
As for the money, it is less money to the doctor if they have no patients.
If he's insane, he won't have a witness, he will just kill them.
Easy stuff there.
As for the patient being in the right state of mind, I am no expert, but I do believe there are ways of telling (such as if they continue with this state of mind for a certain length of time.)
When it comes to life insurance though, that is up to the companies. Believe it or not, many of them are not-for-profit, and that generally means they actually care about the people a little bit more than most businesses.