Do you honestly think a universe the size of ours can only support six billion people before reaching the point of diminishing returns?
That's not my point. The point is people aren't going to be happy if an AI starts making people that are easier to maximize for the sole reason that they're easier to maximize. This will suggest a problem to us by the very virtue that we are discussing hypotheticals where doing so is considered a problem by us.
If you allow it to use the same tools but better, it will be enough. If you don't, it's likely to only try to do things humans would do, on the basis that they're not smart enough to do what they really want done.
You seem to be trying to break the hypothetical assumption on the basis that I have not specified a complete criteria that would prevent an AI from rewiring the human brain. I'm not interested in trying to find a set of rules that would prevent an AI from rewiring human's brain (and I never tried to provide any, that's why it's called an assumption), because I'm not posing that as a solution to the problem. I've made this assumption to try and generate discussion all the problems where it will break down since typically discussion seems to stop at "it will rewire us". Trying to assert "yeah but it would rewire because you haven't strongly specified how it couldn't" really isn't relevant to what I'm asking since I'm trying to get specifically at what it could do besides that.
I put "trivial" in quotes because there are obviously some exceptionally large technical achievements that would still need to occur to get here, but suppose we had an AI with a utilitarian utility function of maximizing subjective human well-being (meaning, well-being is not something as simple as physical sensation of "pleasure" and depends on the mental facts of each person) and let us also assume the AI can model this "well" (lets say at least as well as the best of us can deduce the values of another person for their well-being). Finally, we will also assume that the AI does not possess the ability to manually rewire the human brain to change what a human values. In other words, the ability for the AI to manipulate another person's values is limited by what we as humans are capable of today. Given all this, is there any concern we should have about making this AI; would it succeed in being a friendly AI?
One argument I can imagine for why this fails friendly AI is the AI would wire people up to virtual reality machines. However, I don't think that works very well, because a person (except Cypher from the Matrix) wouldn't appreciate being wired into a virtual reality machine and having their autonomy forcefully removed. This means the action does not succeed in maximizing their well-being.
But I am curious to hear what arguments exist for why such an AI might still fail as a friendly AI.