Earlier quoted context omitted.
First, there is no proof of how much profit comes from nginx in a stack with PHP so you can drop the 'profit greatly' line. Second, the entire point of open source software and the FOSS movement is that you shouldn't be extorted for functionality. Do you harass people that file bug reports or submit requests for features to the Linux Kernel for not paying?
The entire point of FOSS is being able to have the source code of the software you use. Period. That's it. The people who write the software can do whatever the hell they want, as can the people using the software, as long as they abide by the licence. These are the only stipulations. Even RMS supports the right of creators to sell software. People who write FOSS software aren't required to be a charity...
I think this is a point so many users of FOSS miss. I'm an ardent supporter of FOSS, but I don't get to act entitled unless I'm paying someone (and probably not even then).