I think any rational adult should believe in euthanasia. It's an absolutely horrible decision to have to make, but end of life care can be absolutely horrible for the patient. Dying isn't always a pleasant closing of the eyes. Some people can drag on the for months in absolute terrible conditions before passing. People deserve dignity in death.
Of course, the problem with euthanasia lies in where we draw the line. I don't think anyone would judge a 96 year old terminal cancer patient who's just suffering in extreme pain for going through with euthanasia. What about a 96 year old without a terminal illness, but is just miserable and broken? What about a 50 year old? What about a depressed 80 year old? What about a depressed 35 year old? What is acceptable and what isn't?
You only live one life. I think anyone who is diagnosed with something that will absolutely ruin their quality of life should have the ability to end things. When it comes to mental illnesses, I'm not so sure. I don't know if we should help depressed people kill themselves because they are sad when there is a chance to help them.
It's a tricky argument that I guess can't be answered in a Sherdog post.