It's possible that there simply aren't enough Americans who are willing to brutalize immigrants to use the $200 billion they were given.

The SS was 800.000 members strong by 1944 so I think you're wrong, there's plenty of people who are willing to brutalize those they seem lesser for a plethora of reasons - money, feeling of power, ideology, opportunism, hate, the ability to do violence without consequences or any number of combinations of those.