We invest big in private space travel.
Then use the foothold to begin mining asteroids for valuable resources, and of course, searching for kryptonite. If we can find a suitable amount, we could make nanomachines with kryptonite shells, and find a way to introduce them into supermans body. All the while making hundreds of billions of dollars by mining asteroids that can contain as much of an element/compound in them as there is on earth. The added bonus being that it expedites humanity becoming multi-planetary and bursting forth into the future.