Will there be any benefits if we directly provide core source code development for bitcoin? I like Bitcoin very much and I hope to join this community and at the same time have income to subsidize my family.
Incentives for everyone who contributes:
You can be proud of yourself to be a contributor in the full node implementation used by 90% of Bitcoin nodes and one of the critical C++ open source projects.
One more skill added and you will learn a lot of new things: Bitcoin development
If your contribution helps Bitcoin Core and other Bitcoin projects, you might get sponsorship from companies or individuals: https://blog.bitmex.com/who-funds-bitcoin-development/
Maybe make new friends. Although you may have disagreements sometimes with other contributors. People don't have to be 100% friends to work together on a common goal.
I like Bitcoin very much and I hope to join this community and at the same time have income to subsidize my family.
You can work in your free time. We can always manage a few hours per week/month for things that we are passionate about.