Some sociologists and evolutionary biologists suggest that gift-giving as socializing may be wired into our genes.

Whether it’s that innate or not, it’s a human characteristic experts say is spread across cultures and societies. People give gifts to feel good about themselves but also to cement their identity as leaders and to create implicit obligation, even if it’s not intentional.

This article gets into the theory pretty well:

https://www.smithsonianmag.com/smart-news/what-does-sociology-teach-us-about-gift-giving-180948181/