First we really need the Source code of this tool though if we really want this tool to stay for posterity!
"If I make something so great then people will still pay me even if I give it away for free!"
A tiny percentage of people might still pay for it, but the vast majority will not, and will complain loudly about any attempts to monetize.
You said it yourself, this is a hobby FOSS developer. Key word hobby.
Have people stopped understanding that others do things simply because they want to? Not everything is profit-driven, even on this site.
Though I can also understand the child comment on your comment as well. I think that is a reasonable statement as well.
This is a really weird ethical dilemma that I still hold, as a hobby creator myself (just not at a scale of really earning money,but boy I sure would want to ), I want to earn money from it but I also want to distribute it freely, I am not sure how I can get both.
This is true of all products though, in ecommerce 1% conversion is pretty average... generally the path is to increase the top of the funnel because it's always small at the bottom... some products get by with 0.5% or less
What is the cultural significance of this tool that would require it?