[nonfamous]

For your specific case, “take your hard work that you clearly marked with a GPL license and then make money from it”, you don’t even need to rely on fair use. As long as you comply with the terms of the GPL, making money with the code is perfectly acceptable, and the FSF even endorses the practice. [1] Red Hat is but one billion-dollar example.

[1] https://www.gnu.org/licenses/gpl-faq.en.html#DoesTheGPLAllow...

[b3morales]

But the person making money from the GPL code has to follow the terms of the license. Attribution, sharing modifications, etc.

[nonfamous]

Correct. That's why I said "As long as you comply with the terms of the GPL".