Thanks for the calculations! It’s weird how a more advance technology like a jet can be so successful yet an order of magnitude less economical. Usually it’s the reverse. But when you’re rich it’s time that’s money
The short answer is that higher speeds come at a steep price. The relationship between velocity and the power required to overcome drag at that velocity is cubic, so that large business jet requires on the order of 50x more power to fly at 450 kts than it would flying at 120 kts, like the little Cessna might.