Jack knew that he was being followed constantly since the day of the incident and those people were keeping an eye on his every movement. He even knew that he would not get the chance to leave the country before those people killed him and his family. But having no other option he still took the chance. Doing something was at least better than living in constant fear and waiting for them to be killed. It did not matter if he was alone, but he had an old mother, a wife, and his two little kids to protect. Even if he had a one-in-a-million chance of surviving, he would do that. If he could just get to the airport before they could catch up to him, he was ready to give it his all. So, when Kai said that Rain had the power to save them, it elated him as he saw a flicker of hope which may increase his and his family's chance of survival.