> If every single ounce of this gold were placed next to each other, the resulting cube of pure gold would only measure around 22 metres on each side
So that can't possibly be right, you must be off by a factor of 10 or so at least—Wolfram Alpha says a 30m diameter sphere.
It's still a mind bogglingly small amount considering that humans have spared no toil, sweat and blood on industrial scale gold mining ever since the dawn of written history - and since gold is so valuable and hard to destroy, most of it should still exist to this day in form or another.
Yet, if you smelted it all to a single object it would fit on a typical single family housing plot.