You misunderstand. They are going to force everybody to pay $5, then force everybody to use chatgpt. 8 billion times 5 isn't much money, but the advertisers will surely pay a lot for that many captive eyeballs!
At this point why forcing people to use the service, if you can forcefully extract these eyeballs and then sell them directly to advertisers in large enough jars?
(I have no MBA either)