Why should people invest in SpaceX? Because they're going to be propped up by the US government for a long time. Nations need a way to get to space. SpaceX has launched more rockets than anyone in the last few years. Including 3x more than China's space agency.
I'm happy to tell you that Nations don't want to be dependent on the US government and Elon Musk.
So there is a big race to build the next SpaceX. And I can assure you building rockets isn't rocket science. Other companies will follow propped up by their governments.