I'm sorry to hear you're suffering. First and foremost in my mind, whenever I read someone else's story here, is that they have my sympathies.
Regarding your question, I think it's a very personal, subjective thing, with the answer being as varied as the characters who frequent the site. I would say, however, that it's as valid a reason as any other. It's natural to worry about your loved ones, to not want for them to feel the pain of loss. Just shows how much you love them. That's a good thing.
I'm not bereft of sadness for those I'll leave behind. I can't imagine how difficult it'll be for them, at least initially, even though I've discussed this with them. Can I stay alive based on that alone? I honestly don't know. I don't know if I'm prepared to keep pushing forth on the mere chance things may improve. What if they don't? I have to look at all of the potential outcomes, and base the decision on my best guess. I'm still here at the moment, but who's to tell if that won't just change if I manage to secure N? Who knows, it may even be as some of the anecdotal accounts I've read, where people say that having a peaceful means of exit actually prolonged their life.
The way I often look at it is this; with each other, with counselling - if required - and with time, the people I leave behind will find their feet again and move on through life. That's not to say they won't miss me or I won't be thought of, but rather, this is just what life does - it goes on.
Sorry for a slightly longer reply than anticipated. I could have just kept it to "It's subjective and varies from person to person," but I'm very rarely content with giving short answers to interesting questions - I demur.
Again, sorry to hear you're not well. If you don't mind me asking, is this a physical condition affecting your health? or is a mental health condition? Or even both?
No obligation to answer whatsoever, and I'll completely understand if you'd sooner not.