How I like to understand it instinctually is: When you're going up, gravity is working against you. The more time you spend going up, the more time you spend w

How I like to understand it instinctually is: When you're going up, gravity is working against you. The more time you spend going up, the more time you spend with gravity working directly against you. Once you're out of the atmosphere and into the "over" phase, you're not fighting gravity, you're just trying to increase your lateral speed enough that the earth's falling away from you faster enough than gravity's pulling you toward it. Or you can think of the limit case: as your acceleration away from earth goes to zero, your energy spent fighting gravity in order to avoid hitting the ground goes to infinity.