Ownership of your Top Level Domain allows you to take full ownership of ALL Second Level Domains. You are the owner of everything, and can issue the SLD’s as you wish!
With your TLD, you can sell off all of the domain names that support your own Top Level Domain - everything to the left of the dot! You can operate your own registry and sell off your SLD domains or you can issue them to your network as you see fit - the choice is yours.