Also, of course, Zuck's t-shirts are designer and sell for $300-$400 each. The fact that we know this at all means that we're supposed to know. The Swatch watch on the hedge fund manager's wrist doesn't work unless we know that he's a hedge fund manager worth millions and it's a less than $100 watch. Otherwise the "virtue signaling" (a phrase I detest, but oh well) of frugality is lost on the audience.
I don't think tech guys are slobs. They're just wearing a uniform that was set by Zuckerberg et. al. when they codified the Silicon Valley culture. If those guys had worn suits every day, that's what the tech guys would wear. It's the definers of the culture who should be examined, and they only wear t-shirts and hoodies or drive inexpensive cars because they know we fucking love that shit. Blogs, and regular people, eat it up - do a Google search for Warren Buffett's car, for example. It's a very effective and inexpensive strategy for blinding the masses to their exploitation. Of course, Zuckerberg is a demonstration that there's a tipping point to the high-wire act (to mix my metaphors) of both signaling your relatability and humility with t-shirts and looking like a hypocrite. The real problem is, the Swatch watch-wearers still have Rolexes on the inside.
/\ percipient comments BB, just want to point out that slobs aren't necessarily slobs ... clearly somebody wearing a hoodie, t-shirt, jeans, and sneakers the right way can look more pulled together and neater than somebody wearing an ill-fitting suit, knackered shirt, etc. in a bedraggled way, and vice versa