There has been a lot of effort put into designing a space elevator. Gravity is so strong on earth that we need materials that are difficult to engineer/produce.
Why have we not considered the technology for other planets first?
Mars has about a third the gravity as earth. It would be much easier to build a space elevator for Mars.
Even better, there are other places in the solar system that have lighter yet gravity that have resources of great interest.
In order to make space more habitable, we are going to need a lot of fuel. Traditionally this is done by using fuel to launch fuel into space from Earth.
Why not create a robotic refinery, send it to some of the hydrocarbon seas on Titan, and build a space elevator to get the fuel into space? It can then relatively inexpensively be sent to mars or other destinations where fuel is scarce.