I was confused when I first read it as well, but the implication is that the higher reward-seeking risk tolerance can actually be more rational than the well-studied loss-aversion bias that the authors mention.

Looking into this more, studies have found that we tend to rate the possible loss of $100 twice as painfully as the pleasure from the possible gain of $100. This can lead to irrational behaviors.

Increasing the weight we give to potential rewards is not necessarily a bad thing.

I think this can help explain the "calming of the nerves" that slow breathing promotes. If you need to speak in public and your heart is racing and you're shaking, this is an irrational reaction to what ought to be a very safe situation. By focusing more on the rewards (the acclaim for a good speech or whatever) and less on the imagined risks, you can calm down and speak naturally.