What makes something money is not absolutism; it is always relative value - the choice between storing value in one medium vs. another.
To understand why Bitcoin is money, first understand why gold was money. Then, learn what properties make something a better or worse form of money.
- an excerpt from the 2-minute version of Gradually, Then Suddenly (2019) https://www.2minutebitcoin.org/blog/gradually-then-suddenly-bitcoin