Objectively, the money is just a sheet of paper, why? The paper is recognized by the state government to ensure that, so what is the guarantee? that is gold. Which country more and more gold, wealth assets are terrible, that currency is priced compared to other currencies. To understand more about currency you can see the book "War Money" nhé!
Bitcoin is generally accepted by the community and is priced against USD or gold so it's worth it.
In short, every value is converted into gold. But gold has some major disadvantages so new alternatives are available such as money and now Bitcoin.
The clear differences between fiat money and bitcoin is the reason why maybe some do not refer to it as money, as for example and the most marked of all, is the intangibility of bitcoin.
The transactions made by bitcoin are only technological, which impede its absolute mobility. Also, its value is always in constant growth, which gives indications of considering it more as an investment good than as money.