In nature the ill and infirm don’t last too long. Native Americans understood the needs of the many and left the aged encamped st the mercy of a natural ending, which often ended violently.
To be honest, I don’t want a lingering death, nor be left to sit in a facility without a cognizant mind.
There’s a lot to be said for a quick and mostly painless death. Anything less is suffering.
I just want to peacefully in my sleep, unlike the screaming passengers in my car.
But you say you "belong" to yourself, eh? Yes: then if you want to commit suicide, go right on ahead. Private decision, private act. But if you turn it into a public issue by trying to legalize it and medicalize it, you're suborning very serious ethical violations by the legal and medical profession which would make these professions an existential threat to society.
Law and Government are supposed to protect your "Life, Liberty and Pursuit of Happiness," and Life comes first both logically and chronologically, since without Life there is no more liberty and no more "pursuit." Thus legal euthanasia perversely undermines the very reason for Law. Similarly, the Medical profession is supposed to protect the patient's health: and nobody is healthier dead.
So go right on ahead and kill yourself (I am speaking sarcastically: please don't to any such thing) --- but above all, don't corrupt me, or your family, or your heirs, or your doctor, or your lawyers, or your lawmakers and government, the major institutions of society, in doing so.
You believe in autonomy? Then be decent and do it autonomously. Ultimately, nobody can stop you making that choice.