I disagree that reading someone's code is a good way to educate yourself.
I am a developer myself. If I need to solve something, I might go read the documentation and, yes, examples, or watch a tutorial, or ask a question on a forum or Stack Overflow. Very-very rarely would I need to look at the code of someone's program. Very rarely. In fact, I don't remember last time I had to do it.
Another good way to learn is to go work for a company.
In fact, most people in the world are using proprietary software and never were part of a Linux or open source community and yet they know how to program. If looking at code was the only way to learn code, all Linux hobbyists would be the only ones in the world who know how to code, but this is clearly not the case.
So, I disagree that you need open source projects to learn. What you need is a community, not open sourced programs.