What is the right number of unique minds?

That's an ethics question; advanced civilisations are not required to be ethical.

I don’t see how aspiring to be an unethical civilization with a fixed number of individuals is preferable to a civilization that grows and shrinks having pockets of ethical and unethical members.

If the argument is that somehow the former is more environmentally friendly, then I don’t understand why we should accept dystopia for an uncaring god.

A better question is how much any of these minds deserve and what they do to achieve it. Competitive reality is not a dream, it’s pretty harsh. There is not much to have and you can only have so much in total.

Likely below infinite?