But you hold it to yourself to judge what is a sufficient "contribution" from others. You assume this loose-lipped and self-centered position without defining a standard. In other words, you are playing god. Here, you seem to be saying that if there is some impediment to your contribution, then society is to turn its back on you.
Somehow, you seem to know what 'contribution' is appropriate for each individual. What if the contribution of a person is that s/he is an excellent parent and can raise children who will become remarkable citizens? What if a person actually likes working in retail and despite having specific training in a field considered more socially valuable, choses to work in retail? What if some is a musician and never becomes a national figure but toils away as lounge performer or wedding singer or member of community symphonies throughout his/her life?
Are you to judge them? Should you assign them to life of penury? What if, after the death of all of these people, hundreds come forth to say that the children and grandchildren of the parent discovered scientific breakthoughs or created significant public policy? Or that the sales clerk just made a few minutes better for people for years or that the performer had a substantial fan base?
Life is full of intangibles. The worth of an individual may not be measurable until after s/he is dead.