"This is Lady Artoria, the Child of Prophecy from Tintagel. Now is the time for her pilgrimage. And this is Lady Fujimaru Ritsuka, Chaldea's Master, a traveler from another land. When the time comes to drive back calamity in the Town of Iron and the Sea of Coal, the pilgrimage shall be welcomed. The Staff of Selection shall guide her, the traveler from another land shall watch over her, and the child of salvation shall finally reach the throne. The one who sits upon the throne shall be the true king. Please wear a bloodstained crown."
Early the next morning, Boggart immediately gathered Sheffield's citizens. From the castle walls, he solemnly introduced Castoria and Fujimaru Ritsuka to the Goblins and humans below. With Einzbern's prophecy backing them, Sheffield's Goblins immediately erupted in excited cheers.
The Goblins, especially the lower-ranking ones, had always hoped that the Child of Prophecy would appear, defeat Queen Morgan, and save them. The existence tax was a deadly threat to these lower-ranking Goblins. Higher-ranking Goblins had it much better—not because they did not need to pay the existence tax, but because they had money to buy oak.
Within this Britain Lostbelt, oak was an extremely precious resource. Although every major city cultivated it, demand still far exceeded supply. This was because oak could restore a Goblin's vitality, making it immensely important to them.
In the original work, after Mash lost her memories and became separated from Ritsuka and the others, three Goblins found her and intended to sell her off in exchange for money to buy oak. In theory, Goblins had no limit to their lifespans. The main reason lower-ranking Goblins only lived a little over a hundred years was the existence tax. With enough oak, even lower-ranking Goblins could live for a very long time.