You know what makes me laugh? You ask this question of the living. The living arent the issue, and you have no clue how it will be if and when it is you.
So let me tell you something about being terminally ill. There is no refresh button. There is no decision- you don't have any. You don't know what pain you will be in and you don't know the ways in which your body will break down. You dont know if you want to live or die, because living is one pain but dying will stop another- in short, you will die confused.
Yes, people should make their own decision. To live or to die is seemingly simple- but what if it means to live, but with infinite pain? With deformities beyond capability? Euthanasia is just one form of dying but the only form where you preempt nature. I dont know if it is right- in all possibility it is wrong. What should be right is a doctor or nurse asking the patient to communicate their will, and that should be acted upon, and if the patient wishes to end their life it should be so. Anything else is too open to conjecture.