I've said it before and I'll say it again: every single thing Jack does is motivated by love, trauma, or some combination of the two. Jack loves his boys more than anything. He’d do anything for them.
Jack is a leader. He’s got a reputation, and upholding that reputation is what lets him keep leading. He doesn’t lead because he wants the power, he doesn’t lead because he likes to be in charge, he doesn’t lead because he enjoys controlling people, he leads because he cares. He wants his newsies to be okay, and the best way to make sure they’re okay is by leading them. He had to keep that perfect face up in front of them, because they have to trust him.
When Jack takes the money and agrees to shut the strike down, he knows exactly what he’s doing. He hates it. But he knows. He knows he’s throwing their trust out the window, but he also knows that’s the only way to protect them. He very much knows how bad it can be for them, because he’s lived through it. Twice, I’d like to point out, Jack was in the Refuge twice. And if you think the second time wasn’t worse than the first, when Snyder knew he’d been sneaking back to help the kids inside, you’re wrong.
In the third scene of the show, Jack runs. He drags Davey and Les along with him and runs, and then he acts like it wasn’t a big deal, but he still ran. Everyone ran when the bulls showed up, and Jack wasn’t the first one gone. And the look on his face is important! He sees Crutchie being taken away and he knows exactly how bad it’s going to be for him, and it physically hurts him. He does look like he’s being tortured, because he remembers exactly how bad it is in there and he knows how bad it’s going to be for Crutchie.
But he freezes. And he runs. He’s awake before sunrise drawing pictures of what he went through because he has to keep that mask up almost all the time but he has to let it out somehow; it’s no surprise that the trauma that he’s never had a chance to actually deal with or work past pushes him away instead of driving him forward. He’s been hurt and fight or flight doesn’t always help anyone other than yourself.
And when Pulitzer offers him the money, he doesn’t accept instantly. People act like he does, but he doesn’t. He gets put in the basement and he’s angry. He’s so mad. He’s between a rock and a hard place—either he gives up everything he’s worked for, the relationships and trust he’s built, or he lets more people get hurt and probably lets Crutchie die. That’s not an easy choice. That wouldn’t be an easy choice for anyone, but especially not for somebody who loves and cares and tries as much and as hard as Jack does. He’s so mad that he has to make that choice, but in the end, he chooses to help the people he loves even if that means giving up the relationships he has with them.
Do you really think Jack could have ever actually left for Santa Fe on his own? I don’t. I think any savings he ever managed to put away ended up being used to help people, whether that was medicine if somebody got sick or a little bit of extra food when the headlines have been bad for too long. And besides that, I don’t think he could have left everyone behind when they still trusted him. The reason he’s willing to leave with Pulitzer's money is that he doesn’t think he has those relationships anymore. The people were what was holding him back, he’d never jump a train and start over when he had something to abandon. When he decided to take the money, he knew he was probably burning every bridge he placed importance on, and that was why he was willing to take it. He was only really willing to leave New York behind and start over if he already had nothing left. And the only thing he really had to begin with was people.
Jack runs because he’s terrified. He runs because every single painful thing he’s been through is running through his head, and it’s overwhelming. He takes the money because he makes the choice to protect the people he loves, even if that means losing them, and he’s willing to leave because he has nothing left if he doesn’t have people.
So in conclusion yeah stop making fun of Jack for loving, or being mad at him for betraying the newsies, or for saying he’s ready to leave for Santa Fe. He’s a loving, caring, traumatized person who just wants what’s best for everyone he cares about.