Firstly the main reason that it should be illegal is that it can be easily abused compared to physician assisted suicide . For one the act of taking someone off life support prematurely when the odds of survival are very high can happen with euthanasia. The main reason this would happen is if the relationship with the person who is in the coma and the person making the decision is bad they can revive a lot of money from a will. This problem can be avoided with physician assisted suicide and give all the same benefits.
Correct me if I'm wrong, but I think you have misunderstood something here. Euthanasia is peaceful death with the help of a doctor when a patient is most unlikely to survive, which is basically the same as physician assisted suicide. Euthanasia occurs when a patient cannot revive, and is most likely to die after a period of time in which the patient experiences great pain. This is precisely my reason for supporting euthanasia. Do you think it is moral when you leave someone to die in great pain? I think it would be better to let him die peacefully without pain. Also, you said there was a problem in which a person deliberately makes the death happen because they can get a lot of money after the patient has died. Well, I think that can be solved by a vote by all the family members. Even though someone would vote for the death for the money, there is a chance that the person could be stopped by others who do not want the death.