This is a real problem with permissive licensing. Large corporations effectively brainwashed large swaths of developers into working for free. Not working for the commons for free, as in AGPL, but working for corporations for free.
There is a lot of indirect hardly measurable value one can gain.
Going back to the original source: By giving an answer to somebody on a Q&A site, they might be a kid learning and then building solutions I benefit from later, again. Similar with software.
And I also consider the total gain of knowledge for our society at large a gain.
While my marginal cost form many things is low. And often lower than a cost-benefit calculation.
And some Q&A questions strike a nerve and are interesting to me to answer (be it in thinking about the problem or in trying to boiling it down to a good answer), similar to open source. Some programming tasks as fun problems to solve, that's a gain, and then sharing the result cost me nothing.
The bounty is you getting to use my work (shared in good faith no less). Appreciate the charity and don't be a freeloader or you'll get less in the future.