There are so many ways to look at this. The main issue with suicide is that often people decide to do it when they are highly irrational, emotional, or depressed. It is a permanent decision and making it while in a state of mind that is temporary is a terrible loss for both the person and their friends and family. I realize that sometimes people are depressed for a long period of time, so it does not feel temporary to them. Sometimes, these people can enjoy life again with medical or psychological help.
The other side of this is that I do agree there is a time when suicide is not wrong. I would personally rather have the choice to be humanely euthanized at a point where I could no longer live a quality of life that was satisfactory to me. For example, say I lived to 90 and all my friends and family are deceased, my mind is failing, and the rest of my days I'd be forced to sit in a wheel chair in a nursing home staring at the walls and not remembering my name, maybe wearing a diaper, etc. I'd rather go with dignity before that point happened.
I lost my hearing literally overnight 2 years ago due to Sudden Hearing Loss Syndrome. In addition to losing my hearing, I also began to experienced horrendous vertigo attacks and unbearable tinnitus. I saw so many specialists.. A powerful hearing aid and a cochlear implant could mitigate the hearing loss eventually, but none of the doctors could give me hope for the balance issues or the tinnitus.
It was like being tortured physically and emotionally every waking moment. I survived that was for 4 months because telling my parents in a matter of fact way that although I did not want to die, I could definitely not continue to live this way indefinitely and would need to end my life if my issues could not be made bearable. I told them I would pursue every possible avenue of relief before doing that. My parents saw how much I was suffering and seemed to accept it. I did not want to selfishly do it in a way that seemed sudden or unexplained if I had to. Fortunately for me, the hearing aid and the cochlear implant did mitigate the tinnitus quite a bit. I still get it, but can tune it out with real sounds. Ultimately, I'm very glad that a solution was found to make life bearable as I did not want to leave.