Alexander, Napoleon, Hitler, Putin – four studies in Over-reach

What motivates an individual to lead, and thousands, sometimes millions, to follow? Three of the individuals above (no need to say which) led their armies to defeat or retreat, starting with what they imagined was a noble purpose, but finally reaching an ignominious end. Alexander to avenge Persian interventions, Napoleon to force Russia to rejoin the French ‘Continental Blockade’ against Britain, Hitler to reverse the catastrophic effects of the 1919 Treaty of Versailles, and finally the unresolved attempt by Putin to restore Russian ownership of the Ukraine. But here’s the question . . . why did they go on until they were stopped?