What is the meaning of “nothing on the line”?

Question

Snow (Prisoner) appointed to get President's daughter, Emily, who get held in MS One space prison station. Snow saw his friend, Mace, died infront of him.

Snow: Who cares? People die all the time. It's no big deal. How many people have died for you since you got here? But you're the President's daughter, so you're worth it, right? Looks like your little PR trip got all screwed up.

Emilie :I came here to ensure that people were being treated fairly and decently, unlike yourself.

Snow: You know, it's easy to be a saint with nothing on the line.

Answer 1

On the line is an expression adopted long ago from gambling: the line is the area or mark where currency or tokens are placed in making a bet.

So to have something on the line means you are risking loss of the amount you have bet, and to have nothing on the line means that you have not made a bet and therefore have nothing to lose.

Snow thus says that Emilie's virtuous intentions are existentially trivial, because they isn't risking any loss.