They don't exist in the same sense. One exists as material, a chemical composition, with mass and other such properties. The other exists as information. Might you say that YouTube, Google, and Nostr exist? That the New York stock exchange exists? Or that the largest identified prime number exists? (Rather, the record or proof of discovery.) Would you require them to exist in the same sense as water does?
This matters not as to whether Bitcoin is a commodity. What is required is that it is exchangeable, fungible, independent of a specific group of people, and is a basic good (not composed of other goods).
Some things exist as phenomena, like a vortices/tornados, society, or financial systems. These are composed of the motion of other things. Tornados don't exist in and of themselves but are the motion of bodies of air exchanging place, motivated by density differently caused mostly by temperature and gravity. Society is the organization, norms, and interactivity of individuals. Financial systems are mostly formal agreements about how to distribute goods, and the ones that exist are the ones that are enacted. The action of the participants make existent the composition.
Bitcoin is one such phenomenon. The network of free agents agree upon the rules of engagement, and their actions cause Bitcoin to exist.