Bitcoin and PRXY both have a Max Supply of 21 million. However, the two differ in the mechanism of how new supply is introduced into circulation. In the case of Bitcoin, new coins are mined by hardware miners using the Proof of Work protocol by supplying their hash rate to solve computational tasks which are rewarded with the issuance of new Bitcoin. Bitcoin is close to 90-95% fully mined and the complexity of that computational task gets incrementally more difficult as it nears the end of its Max Supply.
In the case of PRXY we are at its genesis, being only a few months old as of writing with a current circulating supply of less than 1.5 million, we are less than 10% of the Max Supply but unlike Bitcoin where hardware Miners are used, PRXY utilizes the Proof of Stake method where stakers in certain contracts are rewarded with newly minted PRXY bringing forth increased circulation supply.