Let's say the gubmint went to the Gates, Ellisons, and Waltons and said "we will appropriate your wealth unless you sign this document which promises to reinvest 99.9% of profits back in the business. Your consumption can be no more than .01% per year of your total wealth."
.01*$1 billion is $10 million, which is probably much more than Buffett or Gates spends per year, even accounting for private jets.
In that case, what is the difference between gov't ownership and private ownership? In both cases, more than 99.9% of the profits are reinvested. Labor takes the same percentage of revenues in both cases, usually around 65%. The wealthy may own an enormous percentage of the wealth, but the vast majority of the benefit of that accumulated wealth accrues to labor. What matters is how the wealthy allocate the profits - that's how they earn their keep in society, so to speak. And as long as they don't blow it in casinos in Monaco, like the Saudi sheiks, they're doing their job.