Is there a psychological reason why buying the "supplies" for a hobby feels just as dopamine-inducing as actually doing the hobby?

I have a closet full of unread books, unused yarn, pristine sketchbooks, and video games I haven't started.

Why does my brain treat collecting the items like a completed achievement? It feels like "Buying Supplies" and "Doing the Hobby" are two entirely separate hobbies in my head, and the buying one is winning. Why are our brains wired like this?