The preamble to the Constitution states: "We, the People of the United States, in Order to form a more perfect Union, establish Justice, insure domestic Tranquillity, provide for the common defence, promote the general welfare..." It doesn't say "guarantee the general welfare." And it certainly doesn't say "give welfare benefits to all the people in the country who aren't doing so well even if the reason they aren't doing so well is because they're sitting on their butts in front of the TV".