"Risk Aversion," as a technical term, means that the utility function is concave with respect to its inpu [...]

Oh, ok. I mean the affect where people make their utility functions "risk averse" to avoid bad possibilities, or just go ahead and avoid bad possibilities, and I have seen people on LW take "risk aversion" (whatever that means to them) as terminal.

You don't "make" your utility function anything; it is what it is. "Risk aversion" just means that the most obvious scale for measuring your utility isn't proportional to your true utility scale. For example, one's utility for money is generally not proportional to the amount of money, and is approximately proportional only if the amount is not large compared to your current wealth.

For larger quantities of money it's not even close to proportional. In particular, I -- and most people, for that matter -- do not value $2 billion twice as much as $1 billion. The positive impact on my life of gaining $1 billion dollars at my current level of wealth is vastly greater than the additional positive impact of going from $1 billion to $2 billion. Hence if I were offered a choice between a guaranteed $1 billion dollars vs. a 90% chance of gaining $2 billion dollars, I would choose the sure thing -- the expected utility of the second option is greater than 90% but less than 91% of the expected utility of the first option for me.

Likewise, suppose that my net worth is $100,000. An extra $100,000 would be great, but losing $100,000 would be disastrous; it would wipe me out. So my gain in utility from gaining $100,000 is considerably less than my loss of utility from losing $100,000... and it makes sense for me to do things like insure my home.

Both of these examples show me to be risk averse. It is not a strategy I have chosen; it is simply a statement of my personal utility function.