I'm confused what selling an open source project would even mean in this context?
You can have it free. And it's ok. But having success is possible too (recheck my examples).
You can refuse to pay. But, if you want support : $$$ for value++. (you just buy the brand)
See this for more info https://www.gnu.org/philosophy/selling.en.html
There's a great difference between selling access to your software and selling your project itself, i.e. the copyright assigned to your code and/or logos, trademarks, etc.