1)  We don't know for certain.  But NK has been run by the Kim dynasty since WW II.  If that dynasty is broken then the PRC would probably install someone rational.  Kim has purged the opposition -- e.g. his uncle.

2) From NK's perspective, the US did more than threaten Libya & Iraq, neither of which had nukes.

3) Since 1950 NK has been a severe threat to SK, even before NK acquired nukes.  Their conventional artillery and missiles, as you know, could decimate Seoul.

4) When Soviet missiles were in Cuba, WW III almost took place.  Kennedy & Khrushchev thankfully were sane adults who negotiated a workable solution to that crisis.  It is impossible to see how this crisis can be negotiated successfully;  that means that war is inevitable.

5) At this point neither the US nor NK trust or respect each other enough to come to any agreement which would
defuse the crisis.

6) The US, UK, France, Russia, China, Israel, India have rational leaders.

NK, Pakistan, and Iran have irrational ones