Sometimes, pilots do the most 'out of character' things. I've lost a few friends over the years, and I've pondered the same thing.
Agree - but then there are also pilots who are consistent with bad decisions or bad handling, who get away with it for a while due to luck. Eventually they come a cropper because their luck runs out, not because they did anything unusual for them. Please note this is a general observation rather than a comment on this particular case.
It is an exact science. It's all about calculating speeds, heading heights downdraughts, demarcation lines......
How can it be an exact science? It is impossible to be 100% sure when and where the downdraughting/turbulence/demarcation line will be experienced. I would say that there is definitely some art involved.