I want to sell the private key of the address that participate the tezos and cosmos ico, who wants to buy it?
No one will buy it since there's no assurance for buyer side that you will not compromise them once they use the wallet you sold to them and also I don't think there's anyone will get an interest to look for private key which participate on what you mention anyways. Maybe you should use that if you think its valuable since you canno get a sales for selling risky things here.