When Paul started off saying he is interested in inequality because he created I was half expecting him to "this is what I've done wrong and I want to fix it". Unfortunately it was another essay to justify "undeserved" wealth in the hands of startup founders.
Paul's essay fails to look at the dynamics of power and money. The amount of money someone has is often a proxy for political power in the hand of someone. Increasing inequality amounts to increasing disbalance in political power. Concentration of political power is problematic because the powerful influence things in their in their favor knowingly or unknowlingly ignoring the rest.
Another issue that Paul fails to address is the reason for economic inequality. The wealth of someone grows exponentially, the money someone has the easier it will be for them to make even more money. That has nothing to do with how much "deserving" they are or how much wealth they have. Sure your startups have helped the world, but that doesn't mean they "deserve" all the wealth they have.
I don't have answer to the problem of inequality, but this doesn't mean the problem doesn't exist.