Interestingly, you must know that any printing equipment that is good enough to output realistic banknotes are regulated to embed a protection preventing this use case.
Even more interestingly, and maybe that could help understand that even in the most principled argument there should be a limit: molecular 3d printers able to reproduce proteins (yes, this is a thing) are regulated to recognise a design from a database of dangerous pathogens and refuse to print.
Gimp doesn't have the secret binary blob to "prevent counterfeiting" and there is no flood of forged money
https://www.reddit.com/r/GIMP/comments/3c7i55/does_gimp_have...
Gimp makes printers now?
So guns are ok? How about bombs?
Because, at the end of the day, counterfeiting money is already illegal.
...and we should not censor tools, and judge people, not the tools they use.