More money !=more in return
Like everything else in the U.S. (and yes I do mean everything) you spend the most money to get the least in return.
A good example is the U.S public school system (grades 1-12) which spends more per student than any other country in the world, (~12k avg. annually as of 2013) yet student performance constantly ranks in the high 20s to low 30s globally* where 1-10 are ranked as best.
While your statistics are correct, the map is not the terrain and that is never more important nor more dangerous if ignored, than in the U.S.
It is the same with welfare. While you SEE a lot money being spent and allocated to the poor, a large share of that money never actually reaches the end recipients.
(* there were a variety of scales, studies and reports to choose from. I chose the averages)