People are all over the spectrum, with people like Stallman and developers at the FSF working mostly on ideological grounds and companies like Oracle only contributing when it would clearly be beneficial to the bottom line.
I used to think I would love to work on OSS if I didn't need money, but I've found that I just like working on stuff, and OSS isn't as much of a priority anymore.
Money is always decoupled from value ( Warren Buffet paraphrased ).
Sometimes people who add negative value like the oil men in the Permian basin get paid 100x then your pip developer.
Screw that, large amount of the surplus generated by technology companies ends up in the hand of land owners instead of stockholders ! let alone the engineers building it - who might be riding on the work of open source volunteers. Its turtle all the way down.
If you are a volunteer, you are forgoing payment and are subjecting yourself to exploitation by others by definition.
Unless you have a mechanism for enforcement you are shit out of luck.
Open source software fails like this even if it's valuable because fixes and improvements don't necessarily make it out into the open, whereas Free/libre software, if it's valuable, gets stronger over time because fixes and improvements must be available to everyone.
Software projects need someone to maintain its course, make sure changes match the purpose of the software, and most importantly, reject changes that create a burden on the project.
Also, I'm going to guess that's something like five active contributors signed up, not five full-time engineers, meaning the actual number once you do the math for availability and such is probably closer to half an engineer. Could be five, but Heartbleed kinda put paid to reasoning like "pip is important, surely it has the funding for dedicated contributors who aren't distracted by something else being their real job."