This could be thought of as Karma.
It’s definitely not instant gratification either, when we do something good for another person, it doesn’t instantly come back to us.
The intentions of positive benefit to another person and result of positive benefit, likely return positive benefits for us!
It’s been “proven” and shown in many ways when we help people, we get something back, maybe not directly, but we get something.
As long as we make it an intention for other people to benefit (not just ourselves) it comes back eventually.
This is one of those believe and it comes true kind of thing.
Believe how you help the world is helpful and truly helping the world and people and it will come back to you.