You can always cheat?:)
Viewing post in New Event of Rex on Final demo! comments
Edit the save to give yourself more money; it's an integer string, it should be easy to cheat it.
Right now, it's in the Registry at HKCU/SOFTWARE/FYMM/DeadDating. I could probably find the exact location or even make a small cheat engine script to locate the money value in the game given it's easy to increment it with the fountain.