And they didn't want you to be able to do that with this event, apparently. Mystery solved.
Exactly. For previous events, you could easily farm more than one hundred of the event currency, which quickly led to a deflation of the value.
For the Chevin event, they tried to increase the value again by adding in the red Sparkle Powder as a money drain, but since most people couldn't care less about social items, they were not in high demand.
The Gree event ensures that you can only get 14+7 gray helices per character per week. That way, people with more characters or more time do not have an advantage over casual players.