I believe the Western Hemisphere was initially explored by entrepreneurs seeking natural resources with private and government funding, and occasionally religious/political refugees (who were not tolerated or who would not tolerate others). Once profit was established then governments quickly got into the act and spent a few centuries defending and dominating their turf with military forces.

As has been pointed out, exploration will not take off until a viable benefit or livability can be found. So far the exploration of Earth-space has taken place initially for curiosity, then for profit, but increasingly for military security as we realize our vulnerability on the ground from space-based threats, and our need to protect our investments and turf in space. Therefore I predict that security will continue to be a primary motivation for the future.

We don't want enemy nations establishing bases in space which could offer them an advantageous access to the Earth's surface, or later mining or weapons sites through the solar system. Eventually we will achieve some measure of colonization as we develop livable habitats. These habitats will grow (human nature being what it is) around major scientific and economic bases, and therefore need to be defended by military bases.