I've always wondered why, if you have a material sufficiently strong to build a space elevator, you don't just use it to wind composite fuel tanks for conventio

I've always wondered why, if you have a material sufficiently strong to build a space elevator, you don't just use it to wind composite fuel tanks for conventional rockets? At 150 times the tensile strength of steel, for example, you could make a pressure vessel that holds 150 times the pressure that you can with steel. Taking the densities as similar (sigma/rho is the relevant parameter) that should make pressure-fed rockets not just viable, but hugely preferable to turbo-pump-fed systems. It seems like you'd recoup your capital outlay much more quickly, even if you did (eventually) use more material to launch an equivalent mass of payloads. For reference, in Engines of Creation (iirc), Drexler outlines a personal launch vehicle that weighed ~100 lbs and could lift a single occupant to leo with one stage. I suspect that the guys that finally do build a space elevator are really just going to end up with a nice place from which to watch personal spacecraft launches.