here is a good case: https://insights.stackoverflow.com/survey/2019#blockchain-in-the-real-world
What will Bitcoin be without these people working hard behind the scenes to constantly improve and secure the technology for us all?
if we believe bitcoin to be decentralized, it should never depend on a handful of developers. and it is not. there are many good developers familiar with Bitcoin protocol and have been contributing to advancement of it. if something happens to current developers (natural disasters, moving on to other things,...) they will simply be replaced.