The goal of all Elon Musk's companies is to advance humanity. He has a comprehensive approach that encompasses development in various critical areas. SpaceX is designed to solve many of the most complex problems, one of which is advancing on the Kardashev Scale:
“To advance up the Kardashev scale, we need to put satellites in Earth's orbit and capture solar energy. This removes the need to build massive power plants on Earth and deal with cooling. Cooling in space is much easier [via radiative heat loss in a vacuum]. The intent of our companies is to move up the Kardashev scale.”