If you go to some public place- you have no control over who will witness your (possibly gruesome) death or decaying corpse. I don't think it's stupid to consider the impact this might have on someone. Maybe they wouldn't give a shit about you in your life- do you care about them though? Maybe they would have helped you. You just don't know. Either way, I'd personally prefer not to impact some random person like that. (Still- I also appreciate that some people simply have no choice. I'm lucky in that I live alone.)
I appreciate that all of this wouldn't be necessary if assisted euthanasia was legalised and readily accessible. Plus- sometimes it is a result of being abandoned by society that leads to an attempt- so- it's partly 'their' fault I suppose. Still- I don't see how inflicting some gruesome sight on a random member of the public does much to compensate for societies ills.
When it comes to friends and family- I suppose that all depends on the friends and family you have. For the abusive or narcassistic ones- yeah- who cares? It's not like they're likely to have the capacity to feel guilty or sad anyway. Still- for those who did care but for whatever reason, couldn't help- again, I don't think it's stupid to worry about how it might affect them.
Again- it does depend on your experience of life. I can understand why someone who has been treated badly by their family and society at large wouldn't feel the need to shield anyone from anything. I'm sorry if this has been your experience.