I think maybe the fundamental issue is something that he said really late in the essay:

> There are other ways to get rich than by starting startups. Some of those do require you to exploit people. But startups are the most common way to become really rich, and if you want to start a successful startup, the key is not exploitation but empathy.

> How people become rich in your society is one of the most important things to understand about it. You can't let your beliefs about this be determined by ideology, or movies, or historical examples that are centuries old. You must look at the world around you and see how it's actually done.

The "it's impossible to do morally" people are looking at how it used to be done, and how it's sometimes still done. They are right to be opposed to that. But oppose the immoral aspects of it, not doing it at all.

And those who hard-core define a billion as immoral are I think signalling something else: They want the government to take that money, from every billionaire. (If we're talking immorality, we could discuss the morality of that.) But they don't understand that there will probably be second-order consequences of doing so...