The novel and the movies make the case that men are blinded by greed and/or lust for revenge, and/or ambition. Rationally, Carlo could never have gotten away with beating Connie twice--the last resulting in Sonny's assassination. But he was blinded by lust for revenge after Sonny beat him up in public. And, he may have been paid off by Barzini, although I I doubt Barzini would have had to promise him anything more than just the opportunity to trigger Sonny's assassination.

For that matter, could Paulie have rationally believed he could get away with "calling in sick" on the day Vito was shot?