Musk is one of my hero's, but his first company was a web start up that help publisher's get news articles and other content online. He then built a money management system, which eventually became part of Paypal. These are hardly the world's important problems. But the exits from these wins allowed him to do what he is doing.
I think that's important to keep in mind if you want to belittle guys building Web 2.0 apps like Flipboard, reddit, ect.
Of course, he got the capital that allowed him to go into these capital-intensive businesses doing internet startup (though at the time he did it, the internet was a lot less mature and he helped move that forward to, mostly with Paypal).
But I still wish more smart and driven people did more important things than photo-sharing apps. It might be impossible to jump directly into capital-intensive industries unless you can join an existing startup (go work for someone like Musk?), but there are also lots of non-capital intensive ways to do very important things that would move our civilization forward more rapidly than one more Web 2.0 company. Same for all the brainiacs who go into investment banking rather than in engineering or biology or whatever. Totally up to them, but it doesn't change the end result.
I think that's important to keep in mind if you want to belittle guys building Web 2.0 apps like Flipboard, reddit, ect.