I want to sell the private key of the address that participate the tezos and cosmos ico, who wants to buy it?
So you participated in te ICO for tezos and cosmos and you must have coins on that address. Will you like to share the public address?
Secondly, when you sell the private key, you will still have access to the wallet which is not a good thing for the buyer. Better send those coins to the person's address who is willing to buy these coins.