The investors added value by providing D'Anconia with capital. Once D'Anconia accepts their money, his duty is to manage it in good faith. Whatever character flaws the investors have (e.g., excessive faith in D'Anconia's management skills) do not excuse him from his fiduciary duty. If he doesn't like owing a share of his profits to people who don't contribute any effort to the company, he is free to liquidate his own shares so he can start a privately-held enterprise.