Well actually, no one was.
We, however, were just stupid enough to start paying for people not to be responsible for themselves.
So, while I understand your argument, I think that it points more towards something that we are doing wrong, rather than something that immigrants are doing wrong.
Immigrants still come for a chance at a better life, we are the ones GIVING them the $$$, if we stopped, they would still come.
That's the way it has always been.
The immigrants haven't changed, we as a nation have.