The uniqueness of bitcoin is 2nd to no others, asides from birthing other Cyptocurrencies, unlike stable coins that are backed by the USD bitcoin cannot be tracked and is highly decentralized meaning that government might find it very difficult to control or influence the price of btc, it is not like the CBDC which is regulated by a nations monetary authority.

 Also, OP just like you stated it is traded in every sphere of the market and can be found in every crypto exchanges because it is the first and most value crypto asset and very easily to be converted to fiat in most exchanges, it might seem impossible to access or trade other Altcoins in most exchanges but bitcoin is most accessible by almost all exchanges.