Legalising euthanasia is the most humane thing to do.I mean, you've also got to account for genetics, the elements, chemical exposure, diet, etc. I've seen 35 year Olds that look 47 and 80 year Olds that look 50, I mean it definitely varies.
And if you let the government get a single toe in the doorway of making decisions about people's actual continued existence...I think that opens up a rabbit hole with some potentially scary ends.
Continued existence for the sake of living is meaningless. Worse so with a degenerative disease or becoming a burden to society or one's family.