Most of what I say that seems negative is actually morose humor. I know (and you probably know) that I'm a fair deal smarter (and many HN readers, including you quite likely, are as well) than the people trusted to run the world. I used to find it disgusting that world was run by such stupid people (with an occasional morally-bankrupt smart person in the mix). Now I find it hilarious. In a perverse way, I take enjoyment in watching powerful people fail at their jobs, with detailed insight into everything that I could do better. You can become envious when you see empty-headed smooth-talkers making millions of dollars for doing absolutely nothing, or you can see it objectively as an imbecilic but utterly comical incineration of resources. There's actually an upshot in that. If we ever tire (as a collective) of those sideshows and reallocate the resources, we can do some great things with them.
I'm positive in the sense that I see potential for humanity to be a lot better than it is. It doesn't even take that much, because things are so stupid (especially at the top of society) that small dabs of smartness can deliver immense improvements. Just being rational and decent to one another would take humanity light-years past where it is. The disturbing thing is that societies invariably form elites that are invested in keeping everything broken, and as people become more distractible, those elites become more entrenched.
For example, while the recent crop of "social media" startups has produced some interesting software, they've done nothing to unseat the existing corporate elite. Real "disruption" means that health insurance CEOs become unemployed, and probably go to jail on manslaughter charges. Now that I could get excited about. VC-istan is just a distracting side show to make liberal upper-middle-class kids thing they've got a shot at the big game, but it's a fun one to watch (and heckle).