I wouldn't underestimate his ability to succeed. He came from nothing, left a secured job in finance for Silicon Valley, then left a secured job in Silicon Valley to work at Facebook. He's used to making decisions that make no sense in the beginning but works out tremendously. How many do you know would do the above?
When listening to him speak, he seems wicked smart. Although some of what he does not make sense, how many others pulled a move like that and still succeeded? Warren Buffet with Berkshire or Bill with Target/Valeant.
Seems to care about giving back with Social Capital and possibly running for governor.
As for Box, I listened to the Sohn Conference and yes - the pitch I thought was assumptive, but if Box was his worst investment - 18% five-year cagr, then he's doing way better than most money managers.
Disclosure: I'm a Chamath/Elon Fan Boy.
