SpaceX has already proven it can land rockets—a failure here or there doesn't matter in the long run.
SpaceX successfully launched and attempted to land another rocket today.
At the moment I'm typing this, we're … not sure what happened. The primary mission of the launch—to put two Eutelsat communications satellites into geosynchronous orbit—went well, and then this happened when the Falcon 9, which is designed to be reusable, tried to land:
The live feed from SpaceX's drone ship cut out because of the intense vibrations of the rocket. The livestream's hosts quickly shifted their attention back to the satellites' journey into orbit. SpaceX employees groaned, laughed nervously, went silent. Did the rocket land? For nearly a half hour, no one knew.
For SpaceX's near future, however, it doesn't matter if any one particular rocket lands. SpaceX's plans to lower the cost of spaceflight by reflying rockets is a long-term mission that's still in what the company calls its "experimental" phase.
SpaceX's is a profitable company, even though it had until recently lost every single rocket it attempted to land. If there are prolonged strings of failures, it might be time for SpaceX to rethink its reusable rocket strategy. But with the landings still in the experimental phase (SpaceX hasn't even proven these can refly yet), failures are to be expected.
Of course SpaceX wants to re-land the rocket, as do fans of the company and its promise of affordable space travel. In the long run, it's going to have to be able to land its rockets the vast majority of the time. But for now, with no stockholders to impress and the basic technology already proven, there's not a hell of a lot riding on any specific landing attempt. It's all about whether or not this works in the long run.
"Reusability is one of the most important goals," Musk has said. "If we become the biggest launch company in the world, making money hand over fist, but we're still not reusable, I will consider us to have failed."
The next step toward that future is actually re-launching one of the four rockets that landed successfully, which the company will try later this fall. As I finished writing this post, Elon Musk tweeted that this rocket did indeed blow up. No big deal: Musk says SpaceX is already working on improving its landing protocols for future launches.