Have to say the simulator part makes me lean heavily towards the pilot crashing it purposefully, from the article -
"The most widely reported piece of evidence tying Zaharie to the disappearance was a course he had charted on his home flight simulator about a month before the crash. Zaharie had a number of hobbies, including paragliding and flying model airplanes, but he also spent a lot of time at home on his computer playing flight simulator games. He sometimes uploaded videos of himself playing on his YouTube channel, where he comes off as affable and knowledgeable, if a bit socially awkward.
In 2014, a leaked Malaysian police report revealed that among Zaharie’s saved flight simulator sessions was a very odd route which ran up the Strait of Malacca, turned south after passing Sumatra, and then flew straight down into the Southern Indian Ocean before terminating in the vicinity of the seventh arc. Not only did the track resemble MH370’s actual flight path, it also contained a number of other intriguing details. For example, the track wasn’t really a track — rather, it was a series of brief clips lasting no more than a few seconds each, indicating that Zaharie had programmed it in advance then skipped along it to various points without actually playing through the entire hours-long flight. Furthermore, although initial reports indicated that the track had been intentionally saved by the user, later analysis showed that it was kept only in the system files, and certainly was not meant to be found. Was this a dry run? It seems too odd to be a coincidence."
Also discovering that black box is a misnomer is mildly humorous, these are apparently orange! - https://en.wikipedia.org/wiki/Flight_recorder