The best intentions...
One of the great mistakes is to judge policies and programs by their intentions rather than their results.
The government decides to try to increase the middle class by subsidizing the things that middle class people have: If middle class people go to college and own homes, then surely if more people go to college and own homes, we'll have more middle class people.
But home ownership and college aren't causes of middle class status, they are markers for possessing the kind of traits--self-discipline, the ability to defer gratification, etc--that let you enter, and stay, in the middle class. Subsidizing the markers doesn't produce the traits; if anything, it undermines them.