Its simple rocket math. Every lb of weight must consume fuel.
Si.pky. 1 lb of weight needs 1 lb of fuel to escape orbit. But the fuel has weight also. So the effective fuel you need to lift the rocket and payload is exponential.
The harder stuff is orbital mechanics. Getting things into orbit is easy. Having thwm go where you want is the hard part.
“most world changing technologies were made because an Engineer was lazy!!!”
-Bill Gates, probably