"I was not sympathetic to the assumption that criminals had radically different motivations from everyone else"

This quote by Gary Becker recommends that he does not think that crooks have inspirations that are significantly different from those of non-criminals. He suggests that bad guys are not driven by some special set of motivations that are totally distinct from those of the general population. Rather, he suggests that lawbreakers are inspired by the exact same fundamental desires and needs as everybody else, such as the requirement for money, power, or acknowledgment. He believes that wrongdoers are not fundamentally different from the rest of us, which their motivations are not so various from our own. This quote suggests that Becker believes that criminals need to be treated with the exact same level of understanding and empathy as everybody else, and that their inspirations must not be dismissed as something totally alien.