I don't think that analogy works well either, given that humans often put a lot of effort into caring for human babies in order that they are able to make it to

I don't think that analogy works well either, given that humans often put a lot of effort into caring for human babies in order that they are able to make it to adulthood (thus achieving "equality" as per your analogy). I think it might be easier for you to explain your point if you didn't describe it in analogy, and instead described it directly. The criticism is that large (i.e. several orders of magnitude) wealth gaps are bad for society, and that they cause tremendous power imbalances in what would otherwise be a democratic society. Purely in terms of wealth inequality, and not through analogy, why do you disagree with this criticism?