Trump's personnel head wanted to fire the defense secretary because he opposed Confederate flags...

Not a single good reason to fire the Secretary

Trump wanted to be king, then proceeded to build his kingdom. He did not care about principles and values.

Trump corrupted the country. Principles and laws be damned, he wanted loyalty at all costs to conduct his nefarious actions. He wanted to be a king and acted as one. His goal was for the kingdom to reflect his persona.