Git exists, because Bitkeeper were being A
holes. [1] A developer needed some metrics on the Bitkeeper repository that Linux used. Remember this is a proprietary and commercial product that granted a handful of licenses to the Linux community as a token of support. So when Andrew Tridgell reversed engineered the format that Bitkeeper used, they threatened to sue him under the DMCA.
This caused a firestorm, some defended him, others defended Bitkeeper, and a lot of people said why the hell is Linus using proprietary software to manage an Open Source project?!?!! Linus waded in and said he'd think about it, I think was on a thursday or friday, and by the next week he had working python prototype of git. [2] The rest is history. Bitkeeper faded into irrelevance and git became the lingua franca for open source projects. Arguably its biggest strength was not revision control, but being designed in manner that many collaborators could seamlessly commit changes for merging. Obviously architected to fulfill the time consuming requirements of Linus Torvalds, it has stood a test of time. I'm writing this from memory, so if it disagrees with Wikipedia take it with a grain of salt.
[1]: https://en.wikipedia.org/wiki/BitKeeper#Original_license_con...
[2]: https://en.wikipedia.org/wiki/Git#History