I started a thread a long time ago with the point that Sonny, who seemed long on brawn, short on brains, made a couple of smart strategic moves with Fredo and Vegas. First, Fredo obviously had a nervous breakdown when Vito was shot. He was useless to the family as a warrior, and a big liability if he were captured and either killed or held for ransom. Sonny arranging for him to be far out of the action, and under the protection of another (neutral) Don was a very smart move.

Second, as we learn later, the Corleones made a big investment in Moe Greene's hotel as part of the deal for Fredo to be protected and to learn the casino business. That was a strategic flag planted in the legal gambling business. And, when the bill came due for Moe, it became the basis of Michael's legitimate fortune in the gaming industry. Well done, Sonny!