One should be able to play witouth a walkthrough.
The part of the game let you spend the money as you want, of course an experienced gamer will only do that when he thinks he doesn't need it, which is exactly what you would think when you get VIP access.
If you're out of money and don't want to (or can't, because the corruption would be too high already) use divine transformation over and over again, you're screwed.
Getting the player out of that position would be so easy though, as you enter the no turning back point, you'd have Charlotte go "Hey, I've made a lot of money, here's 5k for you" and you should be able to survive the fight.