Read this thread over again. There is a sad sentiment regarding Elon Musk's Mansion.
>>Governments can allocate capital more effectively than most billionaires.
Demonstrably wrong. See wars in history.
>>Inequality itself causes social problems.
Like what? Your USSR, North Koreas, Venezuelas of the world. In fact every failed communist nation in the past century falsifies this claim.
>>No single person can really be so much more productive than others as to justify billions in wealth; so if someone is that wealthy, they got that way on account of others' work, so they don't deserve it. Economists are saying we need to reduce inequality to avoid disaster.
Appreciable sentiment if you till the land with a shovel in your hand. Increase of productivity is not always measured through human effort alone. But also through tools which humans invent to amplify their productivity through automation of some kind. There are kinds of effort, one where you do all the work alone. One where you work to invent a tool that does that the job for you. Latter is also commonly known as 'progress'.