The Guru had taught him all but he picked up only that what suited his ambition. Like the lesson we learn from 'Chakravyuh'...unless you know how to break it ( like Arjuna), you could be trapped to death like Abhimanyu.
Alexander the Great learnt under his teacher Aristotle - valour, generosity, passion & brilliance.He literally captured the world.
But he chose to ignore a critical lesson his master had taught him...rule of the Golden Mean!
It is great to have ambitions. It is super to have the strength, will, skill & passion to achieve it. But unless can identify that imaginary line - the 'Point of Enough' , all ambitions topple into destruction & meet a pathetic end.
Power, aggression & flavours of success make a strange concoction. They intoxite & make you delusional. The 'Point of Enough' then appears far away though you may barely be inches from toppling to the nadir.
Endless ambition is easy & so is total complacency. The Golden Mean is the middle ground.The transitioning journey on this spectrum will cross it's 'PoE' and only the wise would recognise it.
Alexander went on and on. His faithful and loyal soldiers had by then got tired. Alexander but would not stop. The soldiers had become home-sick. It is rumoured that they secretly killed him.