After this roller coaster ride, he famously said: "I can calculate the motion of heavenly bodies, but not the madness of people." Joking aside, his behaviour was typical of an early investor who got a decent return, got out, but gets greedy, enters again and this time he holds for way too long.
I am actually surprised by this story. It seems more likely that he bought more after the peak, and then tried to wait until it hit new highs.