shouldn't finding a way to kill yourself be pretty easy, even without legal DWD? you can overdose on OTC meds, or get a knife, or (in America) pick up a gun.
None of these things guarantee death and if you fail they come with some awful complications. Overdosing on Morphine is probably the easiest, most humane way to die.
Someone with sound mind is likely to worry about what’ll be left for loved ones to clean up.
And someone suffering dementia/Alzheimer’s may well forget the plan.