The non-productive members of society (looters, government and moochers) make it more and more futile for the producers/innovators of the world to produce/innovate and place a greater stigma on them for doing so, so they slowly disappear, strike and quit producing. Without their minds, work, innovation and production, society goes to hell in a hand basket.
I don't want to give too much away, but that is a very brief cliff notes version. Definitely worth reading, it is the second most influential book ever written for a reason. Don't read the wiki entry, it will give away too much. If you enjoy reading, educating yourself and social philosophy, you should definitely read it. It is 1200 pages, so be prepared, the first 200-250 pages can be a bit slow, but it is a great book and picks up steam once the settings are set. Very influential book in my life and very fitting for the current economic, political and social environmental.
Parlayin, Fountainhead doesn't compare to AS. Writing and philosophy remain the same, but far more interesting and far better story/characters.