Marc Andreessen says don’t ever do diamonds in the rough. Only do diamonds. "This is actually an investor ego thing, I think, which is you basically say, 'Wow, I'm the investor that's gonna go find the thing that nobody else knows about... I'm going to go do the thing nobody else can think of.'" "The general pattern is... if it's got merit to be investable for venture, there are a lot of really smart and hungry VCs out there, and they are working extremely hard to sniff these things out, and…