There are different levels of danger, and danger comes in more complex forms. The dangers we se in Godfather I are more "street" dangers...i.e. thugs who pose a threat to the olive oil business. In II, as Michael rises in the world the threats to him are just as dangerous...maybe more so, but they are more sophisticated. He is threatened by a U.S. Senator, who he compromises, only to be threatened by an entire Senate COmmittee, all of which is controlled by Roth's man Questadt. He is betrayed by his own brother and he is nearly killed in his bedroom. His most trusted old timer is compromised and breaks Omerta. And then there's Roth, a snake who wants him dead. These guys are all more dangerous than Solozzo, who at the end of the day was a small time drug pusher. In III, the threats are even more pronounced...international financiaers, and the Catholic Church. It doesnt get more dangerous than that.