I remember seeing some documentary about an art forger who donated his works to museums where the authorities were profoundly frustrated that they couldn't do anything precisely because he didn't get any gain.
Edit: the documentary is "Art and Craft" [1] about Mark Landis [2]
> It appears that in donating forgeries to art museums, Landis has not actually broken any laws, even though his activities were clearly deceitful. If he had sold the work to museums or taken a tax deduction on them, he might have fallen under federal art crime statutes. But the fact that he did not gain economically from his actions (apart from a few gifts from curators), and that he addressed his donations to specialists who had the expertise to detect his forgeries but did not, protected him in the eyes of the law. No legal action has been opened against him to date (as of 2014). As one art crimes expert put it: "Basically, you have a guy going around the country on his own nickel giving free stuff to museums."
Edit: the documentary is "Art and Craft" [1] about Mark Landis [2]
> It appears that in donating forgeries to art museums, Landis has not actually broken any laws, even though his activities were clearly deceitful. If he had sold the work to museums or taken a tax deduction on them, he might have fallen under federal art crime statutes. But the fact that he did not gain economically from his actions (apart from a few gifts from curators), and that he addressed his donations to specialists who had the expertise to detect his forgeries but did not, protected him in the eyes of the law. No legal action has been opened against him to date (as of 2014). As one art crimes expert put it: "Basically, you have a guy going around the country on his own nickel giving free stuff to museums."
[1] https://artandcraftfilm.com/
[2] https://en.wikipedia.org/wiki/Mark_Landis