What we can say is that when games are older than one year, digital is a lot more dynamic on console because there are less units in stores. (playstationlifestyle.net)
When the price is high, you end up buying less units whereas when the price is low you get more units for the same amount. (elementummoney.com)
It allows your invested money to earn less units when the price is high and more units when the price is low. (policybazaar.com)