What we have here is one of the posters on their website promoting an invitation/referral compensation program. The initial impact of the image makes one think that it is a pyramid scheme, but if you actually look closely youll understand that in actual fact Kucoin themselves dont really benefit at all, theyre giving 90% of all of their fees to the referee as compensation while they only take 10%. This isnt a pyramid scheme or some shady MLM, its a marketing tool to attract more traders and liquidity to the market. The only people who really benefit are the traders.
I don't think there was a need to post this twice, we got the message the first time 
I think your calculations for the referral bonuses might be a little bit off ( I could be wrong ) but do you have a link to where Kucoin say it's 90%.
Here is an article that says it starts at 20% then increases with each referral, but it would take a lifetime to reach 90%.
"You can earn 20% of fees from anyone that signs up using your referral code (further fees paid from their referrals @12% then @8% for the referrals of your referrals)"
https://steemit.com/cryptocurrency/@cryptomagic/more-on-the-red-pulse-listing-at-kucoin-as-kucoin-gets-listed-as-exchange-on-coinmarketcap