If we combine these two sets of data^1 we obtain a fascinating result^2.

• 46% of all code out there, in every app, is maintained by hobbyists
• 13,8% is maintained by “I sometimes get a bit of pocket money for my code”
• 40% of all code out there is maintained by an industry-paid person

So, nearly 60% of all code being actively shipped in an app or product in the wild is hobbyist-maintained open-source.

See also this discussion on lobste.rs on the economics of the average (as in median) open source project:

https://lobste.rs/s/ftwkvo/hobbyist_maintainer_economic_gravity

To sum up, apparently most open source projects are small, and aren't funded as paid work. And they matter because of their number, which has the effect that they make up a large part of all software in use.