How Much Fear Is the Right Amount?

I've been trying to figure this out.  I don't think I need to
include any links to the evidence, because it's all over the place.
 Some people think there is a ridiculous amount of hysteria
about H1N1/2009, others think people aren't worried enough.  

It is abundantly clear that nobody can predict the future; nobody knows
if there will be a pandemic, and if so, how lethal it would be.
 It is not even possible to make a meaningful guess.

What perplexes me are these two questions: 

Why do people get so emotionally invested in their assessment of the

Why do they feel a need to criticize those who have differing views?

It is sort of like the rivalry between devotees of the Dallas Cowboys
and the Washington Redskins.  Some people like one team.
 Some like the other team.  Surely, people are free
to prefer either, or neither.  Why all the fuss?

It occurs to me that it may serve a social signaling function when a
person declares that the risk of a pandemic is overblown.
 Likewise, it may serve a function when a person declares that
other people are not sufficiently worried.  Such declarations
may be an attempt to gain status, or put down others, or merely to
declare an us-versus-them boundary.

On the other hand, some people really are experts.  They get
to say whatever makes most sense to them.

More like this

What about if the hostility is actually due to how a dominant risk assessment for something like an epidemic/pandemic affects you, whether you agree with it or not? If you think people are complacent, everyone could get sick and die, including you. If everyone's overreacting, it's a big inconvenience for everyone, including you. The prospect of facing the consequences of a risk assessment you don't agree with should piss you off, shouldn't it? Isn't interpreting all this as status-seeking behavior unnecessarily complicated?