I am an owner of KCS which is native token of KuCoin exchange and as a user of Kucoin exchange it makes sense to hold reasonable amount of these tokens.
There are some benefits for Kucoin users if they are holding KCS. You will have your fees reduced if you use KCS. You will earn bonus KCS for holding it from profit of Kucoin which was a main argument for me as it works as a staking. There are some promotional activities directly connected with KCS to earn you some crypto. It has nice pump in the last days, price is quite high now. The token is not valuable outside Kucoin ecosystem so it is strongly corelated with your account at Kucoin.