4K seems waaay too much for a cab most people can't even put in their home.. 
Have you ever actually seen one of those? I looked at one recently, they really are not nearly as big as they look in pictures. They have about the footprint of a pinball machine, but slightly narrower, and they take up less space than a pin, because you don't have to stand behind them. In all truth they barely eat more floor space than an upright, and they eat much less space than a cocktail (cocktails eat an insane amount of square footage once you factor in the chairs).