Octopus Sold! (Just Kidding!)

I have a question. How long do owners hold onto these yachts? With everything getting Bigger (Octopus, Limitless, Rising Sun, etc) when is big big enough? Is there a point where it costs too much to refit to keep up with technology that you need to just build another yacht? Is there a market for these enormous vessels other than the Allens and Ellisons of the world?