So, yeah, you can be for-profit and change the world. Or be for-profit and help people share photos. Changing the world is a pretty big grey area.
I'll confidently bet that Instagram will be "integrated" or forgotten in a few years, relegated to the dustbin of ephemeral "one feature" companies that briefly caught on with hipsters before winning the startup lottery. Meanwhile, SpaceX will still be going strong, revolutionizing private space travel and space cargo delivery, and possibly have achieved tangible milestones toward the first manned voyage to Mars. One company is not much more than an iPhone camera app with a web backend for sharing, is cheap to do, and something that many thousands of developers could do well. The other is doing rocket science, costs hundreds of millions plus, and is staffed by a team of folks of a kind where few can do it well, if at all -- and especially, it now appears, also do cheaply. Humans had tons of pre-existing ways to share photos and "apply cool filters" before Instagram came along. Humanity has very few ways of getting into space (ie, rocket companies), and now SpaceX is one of them. And I respect the significance of democratizing media -- but I felt it was very well democratized in dozens of ways before & without Instagram.
And don't even get me started on Gmail. (kidding!)
Reminds me of some of the recent Valve stories, specifically the anecdote about Doom being the most installed piece of software .
 For those that didn't know this, see the post below and scroll down to 'Valve is different'
Whether you agree with him or not, Zuckerberg's motivation for Facebook buying Instagram was related to the business of Facebook. Elon didn't make PayPal or Tesla start a rocket division, he set up a completely separate venture with its own goals.