Why should anyone do anything for anybody ? Its a social contract, an agreement amongst all living in a community or nation that they will honor each other to a point, help those less able and so on.
Now 500lb people more then likely have done this to themselves, but so many times the poor and elderly, the shut-ins ect don't have the money. Its not the lazy, fat or not willing people it effects, it those listed above.
Think, your healthly and young, when your old, maybe fat and bald and have no job since it was outsourced and you have no medical then say the ame thing. But I doubt you think that could happen to you, or care if it has to others.