You can't sell these contracts in the first place
Have you read the Terms of Service of Steam, Epic or World of Warcraft or any other account based game access? Your account is generally marked as non-transferable in the contract. That means, your rights under the contract can not be sold, given away, gifted or disposed of to a third party. It also means nobody but the signer can become the owner of an account. Most platforms don't even have an inheritance policy and don't transfer accounts even under that special circumstance. In fact, Valve explicitly states you can not inherit steam accounts as of 2020:
Your Account, including any information pertaining to it (e.g.: contact information, billing information, Account history and Subscriptions, etc.), is strictly personal. You may therefore not sell or charge others for the right to use your Account, or otherwise transfer your Account, nor may you sell, charge others for the right to use, or transfer any Subscriptions other than if and as expressly permitted by this Agreement (including any Subscription Terms or Rules of Use) or as otherwise specifically permitted by Valve.
Among the companies that have an inheritance policy is Linden Labs, which have in their ToS state it is not possible to give it away, but who explicitly avail accounts to inheritance by explicit mention in your will as a matter of policy. The banning language in the ToS includes prior written consent of LL, which can be obtained for inheritance reasons as a matter of policy.
You may not sell, transfer or assign your Account or its contractual rights, licenses and obligations, to any third party (including, for the avoidance of doubt, permitting another individual to access your Account) without the prior written consent of Linden Lab.
You gain no ownership
In a physical good, there are cases where ownership can transfer to an unsuspecting buyer. But with accounts that are clearly not transferable in the normal case of selling between an owner and someone else, the would be buyer should have known he could never obtain ownership.