Well I think it was just like a teenager who gets the sudden urge to race which he did regardless of the fact that he was not driving a car but a trainload of passengers.
Again, I will remind people that this Engineer was a Homosexual. I will also remind people that suicide is the number one cause of death for Homosexuals.
One does not race "like a teenager" into a known 50 mph curve at a speed of 105 mph. This was not a thrill, this was a full well known attempt to crash the train.