Everything points to it.
- Turning off all communication right on the Malaysian/Vietnam border (can only be done by pilot or co-pilot)
- Doing sharp U-turn then flying right on the border of Malaysia and Vietnam moving in and out of both countries airspace on multiple occasions causing confusion in traffic control towers.
- Doing series of sharp banks around Penang (the pilot's home town) perhaps as a final farewell
- Wreckage discovered so far points to a controlled landing (again can only be done by a skilled individual like a pilot)
- Very inexperienced 27 year old co-pilot on his first flight. Would be easy to order around such a rookie.
- Cell tower information has co-pilot trying to make a call from the doomed plane.
- Investigators found flight simulator at pilots house practicing the same route MH370 would eventually take.
Alot of this points to the pilot and not accident like an onboard fire or bomb.