Hey there, glad you are enjoying the game!
What if I limit the maximum bet size a little more, just to keep the situation from spiraling out? Grinding becomes less worthwhile if I increase the necessary time by 10 or 100. I might also add a "soft cap" by manipulating the odds after a certain threshold for the day. I didn't do it before because I felt like the game gave enough money anyway, but we players tend to min/max wherever we can.
You are likely not stuck, but you must make sure to fully exclude all potential candidates, by having a "full profile" for all of them, even if logically you can already tell who's the one to convince. Since Navarra's powers aren't perfect, she wants to be sure you know as much as you can before you act.