Different assumptions would yield slightly different results, but the general magnitude would be similar. What do such highly categorised calculations tell us? They do perhaps tell us two things. In the first place, they tell us that it is hard to provide pension security of the assumed level solely through a funded pension scheme.
It is not possible to maintain funds worth six times the value of GDP, not nationally, and particularly not globally. The supply of productive investments would quite simply run out. An economy with real assets worth more than six times the value of GDP would be strongly overcapitalised, and its return on capital insignificant.