Why is there no option to upgrade the pre-purchase with money directly?

[Leynea.2613]

I'm aware that upgrading from Standard to Deluxe can be done with gems, but there is no way to upgrade from Deluxe to Ultimate. And I fully understand why upgrading with gems can't be done (I mean you'd basically be paying gems to get gems).. but why isn't there an option to upgrade from any version with real money? Most other games have this option for their expansions even after launch.

[Inculpatus cedo.9234]

Use real money to purchase Gem - upgrade to Digital Deluxe. 

 

Alternatively, within the first 30 days of purchase (barring Ultimate, of course), obtain refund and (re-)purchase the more expensive edition.

[Forgotten Legend.9281]

chargebacks on your card will result in a perma-ban on your account... so if you already added the code to your account, it gets complicated. support ticket only... don't ask your card to cancel the charge.

[JustTrogdor.7892]

The reason you can't upgrade from Deluxe to Ultimate is because the only difference between the two is the gems that are half price.    The Ultimate is there to entice players to spend the most at the time of purchase with the benefit of half priced gems.   It's a bonus for buying the most expensive package at the point of sale.