Even though Lyndon Johnson's presidency was in many ways scarred forever by the war in Vietnam, and destroyed in a lot of ways, he - as a character - was even larger than his presidency. Being able to get to know him well, that firsthand relationship with this large character, I think is what drew me to writing books about presidents.
Regarding ego force, we don't always like people who have it. If you have it, and need to be liked, you ought to consider letting most of it come out the end of your brush.