Flying looks easy. It can be, but it can also kill you faster than you can say John F. Kennedy, jr.
This is what pilots understand that most people don’t, and it’s something that might seem very basic (but it isn’t):
The spatial understanding of operating a very fast vehicle in 3 dimensions, actually 4 if including time, and then performing that task without any visual references. Adding the extra dimensions greatly complicates the problem, as you must not only master the horizontal, but also the vertical. Mastery of roll, pitch and yaw are also added to the equation, plus a pilot must know exactly where they are in relation to the world at all times.
That’s what separates flying from driving or boating. Unlike driving or boating, an airplane can’t pull over and stop. It must keep moving until it lands, runs out of fuel, or impacts the ground. If a car slows down too much, people behind them might honk their horns. If an airplane slows down too much, it will fall out of the sky, spin, and crash if corrective action isn’t immediately taken. Running out of gas in a car or a boat is inconvenient. In an airplane, it’s deadly.
Things happen fast in an airliner. An airliner can exceed ground speeds in excess of 750 mph, and a pilot must be able to think faster than the aircraft can fly. Get behind the aircraft, and it will blindly fly you into the ground or the side of a hill.
Failure to be proficient in operating an airplane in 4 dimensions, or in staying ahead of the airplane, are the number one causes of flying accidents. Most people are unaware of this fact until they undertake formal flight training.