Why would it be a selfish act? Unless you were a family man or something, I don't see how it could be selfish.
What if everyone around you WANTED you to kill yourself? Then you would be doing a service to those poor people.
Take me for instance. Just about everyone I know hates my guts and openly wishes for me to die. I don't kill myself simply because I enjoy making other people mad.I could just get with the program and hang myself in the garage and I even have a noose already made, but I don't do it.
Only because when I think of how happy everyone would be if I was dead, it makes me sick. I would rather be alive and miserable and make everyone else miserable, than be dead and happy, and make everyone else happy.
So in my case, being alive is the most selfish thing you can do!