Captain Nemo's utopian underwater city was a real Utopia because everyone knew everything about it. The Utopia came closest to extinction when a group of stray survivors of a maritime accident were imprisoned in it against their expressed will. In the absence of choice, no utopia can exist. In the absence of full, timely and accurate information, no choice can exist. Its members are immortal, don't have to work, or think in order to survive.
Sophisticated machines take care of all their needs.
No one forbids them to make choices. There simply is no need to make them. So the Utopia is fake and indeed ends badly. Greedy, thoughtless money machines in the form of billionaire tycoon-producers exploit Truman's life shamelessly and remorselessly in the ugliest display of human vices possible. The Director indulges in his control-mania.