What the benefit to using black, platinum anda gold card for special investors? I did not see it in the whitepaper
Black Card (Ranked 150); 5% discount for 10 years；
Diamond Card (Ranked 51150); 5% discount for 5 years；
Platinum card (Ranked 151300); 5% discount for 3 years;
Gold card (Ranked > 300; Contributed >10 ETH); 5% discount for 1 year.
For any purchases using X POS device on any of our stores