The circulating supply is important in crypto because once multiplied by the per-unit price, investors can better understand the approximate valuation of various cryptocurrencies, also known as the market cap. To do this, simply take the circulating supply and multiply it by the current market price of the crypto.
So, if there is a circulating supply quantity of 100,000 crypto coins and the current market value of the coin is at $5.00 each, that means the market cap is $500,000. Figuring the market cap is important because it can be used to help determine the overall risk and stability of crypto that you might be considering investing in.
Generally, a cryptocurrency with a greater market cap (greater than $10 billion) means that it is less likely to be affected by significant fluctuations in the market, hence it may be a safer bet in terms of investing.
Whereas a cryptocurrency with a lower market cap (less than $1 billion) is greatly affected by significant fluctuations, such as if a holder with a lot of tokens sold off their supply.
Ultimately, the circulating supply of crypto is an important metric to know, especially if you are considering investing in crypto.