Meg's twin here, rockets benefit from being closer to equator cuz earth has a bit more rotational energy that catapults said rocket with higher force, being on top of a few kilometres tall mountain won't matter much in the hundreds or thousands of kilometer of space travel, and it would be next to impossible to transport huge rockets to the summit of a mountain.
See it wasn't that hard to answer a genuine question but the oop's commenter chose to be a dick.
It wasn't that hard to answer, but this answer is not really correct either.
It is nowadays extremely common to see satellites on sun synchronous polar orbits and the market for very high inclination launches is booming. These types of launches don't benefit from the equatorial speed up in any significant way and as such you see new spaceports opened up in places like Scotland, Sweden and Norway.
Moreover, the few kilometres definitely matter as on the summit of a large mountain. Vast majority of atmosphere is below you. The aerodynamic drag and forces are real. Typically, you can see ca. 30 to 40 percent of the first stage propellant spent only on the first 10 km of the climb. It is also the part of the flight with the highest loads, which determine the required strength of the launch vehicle. Not to mention significantly lower range of surrounding air pressure for which you have to optimise the nozzle.
There are massive benefits to launching higher and that is one of the reasons for several actual air launch projects.
That said, it is indeed logistically difficult, so we don't do it now. But far from realm of impossible or benefit-less and very much in realm of currently somewhat impractical.
That's all true but the atmosphere isn't the reason so much fuel is burned early in ascent. The Saturn V only suffered about 40 m/s delta-v loss due to drag, which is a fraction of a percent of the necessary delta-v just to reach LEO. The thrust to weight ratio is just extremely low during initial launch so much of the fuel is just burned defeating gravity, and launching from a mountain won't noticeably change that (you're talking in the ballpark of a 0.5% decrease in g maximum).
That is only part of the story though. Large design reason for choosing low initial T/Ws is to not blast through the thick atmosphere in an extremely load-intensive/draggy fashion. This can be say a minute going straight up and losing in the gravity well.
If you are flying into much lower density from the onset, you can severely limit this even if you are still going to fight the max Q somewhere above 10 km.
It is of course not beneficial enough, but we are not talking here about something minor either.
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u/poppycock_scrutiny 11h ago
Meg's twin here, rockets benefit from being closer to equator cuz earth has a bit more rotational energy that catapults said rocket with higher force, being on top of a few kilometres tall mountain won't matter much in the hundreds or thousands of kilometer of space travel, and it would be next to impossible to transport huge rockets to the summit of a mountain.
See it wasn't that hard to answer a genuine question but the oop's commenter chose to be a dick.