I'm a pretty calm person. I hardly ever raise my voice. I also don't usually get extremely excited about stuff.
That's not to say I don't think things are cool. On the contrary, I see cool stuff all the time and tell people about it constantly.
It's more that it is not in my personality to be as likely to be emotionally taken with stuff as much as others seem to be. For example, I know a lot of people who get extremely impressed with other people's accomplishments when they meet or read about them. It manifests itself in statements like "X is amazing at Y. He/she revolutionized/invented Z."
Don't get me wrong -- I generally find these people interesting, as I find most people interesting and love to hear their stories. But I rarely put them on a pedestal in the same manner, and I know some people find it off-putting.
It works the other way around though too. I find it a bit off-putting when other people get extremely excited about seemingly run-of-the mill stuff. I guess it feels a little boy who cried wolf.
I suppose my threshold is just a lot higher. I'm more excited about two or three standard deviations when other people seem to get enthralled by one.
I don't get offended and riled up on the negative side as much either, politics or otherwise. This personality trait has definitely increased with age. As a teenager I definitely got more exited about stuff in both directions.
Not that I can control it, but aside from being off-putting to some people, I think it has helped me manage the startup career path. I have up and down moments like everyone else, but they don't seem to hit me as hard. I generally don't get taken with fads or "celebrity" endorsements/advice. It helps me stay on critical path and work toward a long-term vision.
I'm not saying this way is better. Being personality driven, there doesn't seem to be much choice in the matter anyway.
Along time ago I thought it might be apathy, but I was wrong about that. I'm not apathetic. In fact, far from it. Now I'm just more secure about who I am and understand it's just part of my personality.