Well it sure is good that this random new character showed up with a sob story to justify their attempt to destroy the city's economy after the fact!
The elf going "yeah don't worry the adventurers will figure something out" also doesn't mean anything in regards to like, the people who actually live in the city, lmao. Sure, the travelers will go home, but they're the ones driving the business in the city, along with the dungeon. What about the people who actually live there? What are they supposed to do when the economy craters? "Yeah, just go live somewhere else, I gotta make cash off of carbonated potions, sorry."
It doesn't really seem good for the adventurers in the long run, either. They say that the adventurers want the potions, but why do they want the potions? To do their job in the dungeon, which... is about to be destroyed. Setting up shop for sparkling potions in this city is meaningless to them without it, so how is this supposed to be helping adventurers? Unless MC's group plans to take the business to another city, in which case they've just destroyed this city's economy for no reason. The adventurers want the potion and the dungeon, which isn't something that MC's group is going to give them.
They do a good job of focusing on the meanie merchant guild and adventurers here, while ignoring the rest of the people that will be affected by it (including the normal citizens which made the girls aware that what they're doing might affect people negatively in the first place). This whole thing annoys me, lmao.