I think better is buy Cryptopia coin. Its name Dotcoin and price its only 0,07$ if you all talking about exchange's coins.
Owning DOT does not give any share of the profits. DOT is currency used to pay to list a coin on Cryptopia.
Owning Kucoin or COSS will give you 50% of the trading fees which can be quite substantial amount in passive income if there are hundreds of millions or billions in daily trading vol. Like fractions of a cent X hundred of millions or billions becomes many thousands of $