It is true, bitcoin developers have being increasing over the years but with recent happenings, don't you think bitcoin need more developers?
Bitcoin is a decentralized project and has decentralized communities from developers to users so that there are always many open gates for people to join it as either developers or users.
There is a donation page for Bitcoin developers but they are most famous and productive Bitcoin developers. There are more developers who are less famous and behind the scene.
https://bitcoindevlist.com/You can become one of Bitcoin developers if you want and have skills. The gate is always opened for everyone.