[eli5]Building a sky elevator

Question

Why instead of launching rockets from the ground, we don’t build a high platform above the sky and launch from there?

In: Earth Science

Answer 1

In concept launching a rocket when it is already outside the atmosphere would save a lot of fuel and be easier to reach orbit.

All you need to do is build a structure at least 200 times taller than the tallest building ever made. Simple, no problem, why don’t you get right on that.