Your statement that Trump is unstable is completely incorrect. Since neither you nor the Demoncrapic party has figured it out, I'll spell it out for you..
His display of personality and narrative shifts is a tool to keep his opponents and competitors off balance. He's a master at intuitively achieving leverage over an opponent, given the way the opponent if wasting time and energy second guessing Trump. By the time an opponent has made a decision regarding some issue with Trump, Trump has already moved on.