People like the Kims don’t stay in power by being stupid or insane, even though we seem to have this strange psychological need to belittle our enemies.
Kim has what he needs: Enough nuclear weapons to make taking him out like Saddam or Khaddafi much too risky for everybody who might consider it. Mission accomplished.
So for now he can negotiate, offer concessions, even stop any further nuclear program, do whatever gets him stuff, works to his advantage, and helps stabilize his power.
Whoever “wins” this round, it’s not going to be the people of North Korea.