Why didn't Alexander the Great conquer Rome? (Short Animated Documentary)

Alexander the Great did not conquer Rome due to several reasons: 1) His father, Philip II, had promised to attack Persia, which was a unifying force in Greece. 2) Alexander likely knew very little about Rome, which at that time was not a regional power. 3) After defeating Persia, Alexander had to pacify the rest of Persia and put down revolts, which took six years. 4) Alexander's intent was to conquer places like Carthage and he likely didn't know anything about Rome. 5) The Greeks had minimal contact with Rome and wouldn't have cared much until Rome's conquest of Greek cities in the south of Italy, which happened about 50 years after Alexander died.

via Why didn't Alexander the Great conquer Rome? (Short Animated Documentary)