I think I see the disconnect here. I had forgotten that, as Lucio put it, "The Laws have nothing to do with right or wrong," so I was assuming that breaking the Laws made you evil.
Also, I remembered something I read that seems to present a good parallel. The army discovered a long time ago that all humans have a sort of mental block against killing other humans, hardwired into our emotions. So what they do is they take recruits and they subject them to battlefield conditions: chaos, explosions, noise, etc, and they have them "kill" targets over and over until the very instincts of the soldiers have been rewritten, so that when they are under stress their default setting is "Kill!". All armies have to do that, the good as well as the bad. Perhaps breaking the First Law does the same sort of thing.