That's like saying, you will never convince me that I have to help my neighbor when someone shoots at his house.
Yes, under normal circumstances you don't have to help your neighbor. You have no legal obligation to do so, but what if the person shooting is wearing a Swastika or a Rising Sun flag on their arm? What if it's war time? What if thousands of your neighbors are being shot at? Our country has come to an agreement that we will support each other through extraordinary means in such a case.
Now, the same can be said about abject poverty. Just as we've said that we vow to support a government who's job it is to provide for a common defense, we've also said that we will support a government that promotes the general welfare. You may not be legally required to feed a hobo on the street, but you are required to support the government who's task it is to make sure there aren't thousands of impoverished elderly folks just like it's the government's task to make sure we're collectively safe from physical harm.