*his 'hard' cash
I assume that the writer is not familiar with the actual comic book stories of Scrooge, which are ~30 years older than Ducktales. His Money Bin holds all of cash, which doesn't actually circulate. Also, measuring velocities with m/s2 as a unit?
On How Much Money You Need To Realistically Recreate The Scrooge McDuck 'Gold Coin Swim'
*his 'hard' cash