While you’re right, the MTOW of a B-26 is around 17 tons, the 767 is 150-200 tons.
So there is a factor of around 10 between them, so if the 767 flies 3 times as fast - which it doesn’t, the B-26 cruises at more than 0.35 Mach at close to sea level, and the 767 is not supersonic - that means that the factor from the speed can’t be more than about 3 squared, so 9.
So the factors from the weight and the speed are roughly equal IMO.
While you’re right, the MTOW of a B-26 is around 17 tons, the 767 is 150-200 tons.
So there is a factor of around 10 between them, so if the 767 flies 3 times as fast - which it doesn’t, the B-26 cruises at more than 0.35 Mach at close to sea level, and the 767 is not supersonic - that means that the factor from the speed can’t be more than about 3 squared, so 9.
So the factors from the weight and the speed are roughly equal IMO.