> The problem with just taxing it all away to prevent him from being a billionaire is the money is tied to control of the company, so it's equivalent to saying nobody can build a business bigger than some arbitrary limit.

Limits are hardly arbitrary. If you control a large enough chunk of economic output that your decisions have distortionary effects on other markets and people it’s not an “arbitrary” standard that this should be disallowed. I assume everyone on HN would be pretty pro something like net neutrality to constrain gatekeepers from carving a slice out of all business done on the internet for themselves on these grounds. But, for some reason, people seem to have trouble connecting how the same logic applies to distortionary control over the media or something like urban transit.