China Plane Crash Black Box Points to Intentional Nosedive

People who are so depressed that they commit suicide usually stop going to work long before they take their own life.
It's possible but unlikely.
Wouldn't pilots have regular medical screenings, since so many lives are in their hands?
This pilot could have had anti social personality disorder and been sociopathic.
But terrorism seems more likely.

Yikes she is ugly

the first officer was a very experienced , long term captain who was punished by demotion to first officer for some incident . the captain was a young , recently promoted guy
who happened to be the son of the man who demoted the fo .
if it was deliberate the culprit must have gotten the others
to leave the flight deck . there was 3 pilots up front .

You're painting the scenario like it was just another day and not planned months (if not years) in advance.

Jihad doesn't happen overnight. Instead these people train for years (decades).
“When the sacred months have passed, then kill the non-Muslims wherever you find them. Capture them. Besiege them. Lie in wait for them in each and every ambush but if they repent, and perform the prayers, and give zacat then leave their way free.” Koran 9:5

But this incident happened 24 hours after China backed out of a Saudi oil deal. After the plane crash China was more pliable to negotiate.

Indeed.
Just like 911 wasn't a sperm of the moment idea. The seeds were planted in the 1970's.

maybe it was boeing software programmed to nosedive and crash the plane into the ground to stop it from climbing steeply and maybe stalling? it took boeing hours to program that autopilot software!