I don't think they flew it to crash it. I think their fuel planning was inadequate, but it is also possible in their efforts to evade detection, that they caused an unusual attitude that, due to their inexperience, caused them to get vertigo and crash. The big black ocean some scattered lights and then nothing, vertigo city. Vertigo is easy to get, easy to not recognize at first, takes a good bit of experience to overcome once it has you, will crash an aircraft as fast as anything else.
I think it is entirely possible that the mission planning for this on the terrorist's side was a globe and a string. I think they waited too long to start, then wasted time with control measures within the aircraft and trying to avoid detection instead of getting on towards their destination. Their altitude selection probably didn't help. Fuel consumption changes with altitude, as it does when you aren't smooth on the throttle.
OK... so you think it was terrorists - but they screwed up?