I doubt you would find many people who disagree with you the person taking his life does it with motivation similar to what Gameface posted above. However, many who commit suicide honestly feel they are taking a burden from their loved ones, that their loved ones would be much better off without them. These are people who simply aren't thinking straight. If a person does it motivated by the thought that they are making the lives of those around them better, how can that possibly be a selfish act - at least in their mind? You and I might see it as selfish because we are not dealing with the same demons they are and we can think more rationally, but if you see things from their perspective, it simply wasn't selfish as they see it.
I distinctly remember one very very bad day. I had been in a very foul mood for a few months. Normally the bad spells didn't last that long but this one was really bad. I had been angry at God for a long time. Also stress tended to set me off and I was working at amazon, and at holiday time no less, and we had just moved into a new house, so my life was nothing but stress. I wasn't sleeping and that made things worse. The last thing I wanted was to be around people, so I shunned everyone. My wife and I had been fighting, severely, for weeks.
This day it all snapped. She threatened to leave me and take my kids away from me since I "obviously didn't love them anyway". She screamed at me in our room that she deserved the man who I used to be, that she deserved a man who wanted to go to church, who loved the Lord, who honored his priesthood and wanted to be part of her kids life, one that didn't just work all the time then lock himself in the bathroom (we had an awesome jetted tub and I could stay there for hours at a time) or office and never see anyone.
The kids were in their rooms crying, I could hear them, and I knew it was all my fault. I sat on the floor with my head in my hands, with nothing to say. Tears flowed, I couldn't make a sound. I begged her to stop, told her I was sorry, told her I would be better. She said she didn't believe me. I knew she was right, about all of it. I finally stood up and went to the kitchen to get a drink, shaking all over. All I could think of was how she was right, how much damage I was causing my family. As I passed my daughter's door she had it open a crack and was peeking out. As I passed by and looked at her she recoiled as if in horror. I heard her leave her room and go into mine as I turned the corner in the hall. I got a drink of water and went back down the hall, meaning to go into my office and get on the computer and bury myself in a fake life somewhere, hide from all of this.
Outside my door I heard her talking to my wife, who was sobbing. My daughter asked if I was leaving, and my wife said she didn't know. Although I never had raised my hand against my kids in anger, my daughter then said she was afraid of me, that she didn't want a mad daddy anymore. Physical pain isn't the only kind you can inflict due to this kind of thing, and far from the worst. My wife agreed with her and didn't say anything in my defense. Finally I heard my wife ask my daughter if she wanted me to leave. In her tiny 6 year old voice she said "yes I do", and they both cried.
I immediately went into the garage, got into the car, started the motor and rolled down the windows. I wanted nothing more than to rid my family of the cancer that was me. I hoped this would be the easiest, least painful way to do it. I wrote a note, held it in my hand, and slowly faded out.
I have no idea how long I was there before my daughter came out to ride her bike and opened the garage. I woke up and had a vicious headache, and I noticed the garage was open, found out later she had opened it to go bike riding. She must have seen me there, probably thought I was asleep.
I got out of the car and slowly went back inside, but I stopped long enough to destroy the note before I did, and puke in the garbage can there. I was profoundly disappointed I was still alive. But what tore through me was the fact that my wife and kids would be even more disappointed. That they didn't want me anymore, and that I KNEW I was bad for them and they were right, they would be better off without me. I felt I had let them down by not finishing it.
I didn't think I was being selfish. I thought I was setting them free.
That was a bad day.