This shows the character development from the CvV series to the Unstoppable series. Even though Amy denies it pretty much the whole time in Unstoppable, Jake has pretty much learned how the Cahill family works in the way of taking risks. I'm not saying that Jake takes the right kinds of risks in Unstoppable (cough cough Breakaway cough cough), but you can tell that he isn't as afraid anymore, just ready to end the war for the Cahills.
Yeah, by the end he's definitely not afraid anymore. Not always the wisest ;) But definitely not afraid!!!