How to become a Linux source code maintainer?

According to [this link](https://opensource.com/article/18/8/first-linux-kernel-patch) , when changes to the Linux source code are submitted, they are reviewed by a hierarchy of maintainers, eventually concluding with Linus himself. How does one become such a maintainer? (Context: I'm teaching a class about the basics of Linux and one of my students asked this, and I'm having trouble finding a satisfying answer online.)