I think this is about as simple as overall left vs right debate which it is a part of. There is no "right" or "wrong" here, just "right" and "left". It's a matter of who wins, and both sides have their reasons to play hard to win.

I hope assisted suicide never becomes legal here. It’s just another way for society to fail.

You’re assuming that a society without the right to die isn’t already in a failure state.

If you’ve got one problem that could kill you then inviting in a second does not seem like an ideal choice. A little plague to go with that yellow fever, perhaps?

No matter what there comes a problem that will kill you. You don’t get a choice in that extremely fundamental fact, it’s a consequence of both the fact of your life and whatever rights your country permits to you in that life… plague, yellow fever, ruptured peritoneum, or a GBU-57 ejaculated by a very small orange fungus masquerading as the penis of a grotesquely inhuman man, thou shalt shuffle off this mortal coil. If you can’t choose to shuffle it off yourself you’ve already accepted the loss of the one freedom every living thing should have from moment zero.

Is there evidence that society fails?

What, aside from history?

Please elaborate. Which society or societies, when?

You can’t think of even one? Not even Rome? Do I really have to list out all the failed societies here?

List out all the ones that failed due to assisted suicide, yes. Maybe just two to establish the outlines of a pattern.