Would be better if the heroes were taught NOT TO DO STUFF THAT IS HARMING OTHERS, in the first place. So what's going to happen when they finally tick off someone big, like that Demon Lord that had signed that peace treaty with?
The MC isn't making enough to offset a kingdom's economy. Just remember, he's one guy and though his cheats allow him to do the work of a small group, it's just that, a small group. He was meant for the Hero Group, before the idiot king kicked him out. That magic sword he made? It cost him plenty in both materials and kettles. And it's not like he isn't spending huge amounts back into the economy. Remember that kitchen set he bought for Pochi? That was a whopping 300 million kettles.
Pft... did you even read this chapter? In just a few days he made crates of potions that would likely take an apothecary guild weeks if not months to produce. A page or two later he adds enough enchanted swords, armor and equipment to outfit around 30 to 40 soldiers/knights. Again the products are produced
AND enchanted in just a few days. To top things off, he crafts a sword worthy if being a Hero's main weapon while they fight the demonking as a lark.
In this one chapter part the MC did few months worth of work for three or four different guilds! Alchemist, weapon/armor smith's, and enchanter guilds. And let's not forget that sword a weaponsmith would consider a lifetime achievement.
In days.
Now let's talk about the cyclical economy. Adventurers collect loot to sell to the guild and merchants. Crafters and businesses buy materials to produce food, daily consumables, potions and equipment. Adventurers, businesses and governments then purchase those goods. Living expenses and taxes will also be factored in as well.
The MC on the other hand collects the vast majority of the crafting materials, including the currency for upgrades, himself. He then produces food, potions, equipment and weapons in mass. He also enchants and upgrades the applicable items for funzies. Afterwards he hands it all over to his convenient merchant friend which is then sold or auctioned off. And then the cycle repeates.
While true taxes and transportation fees can be had from moving and selling the finished products, it still cuts out every other step of a multilayered system.
As for the kitchen set, it's hardly a drop in the bucket. The MC spends as much on just few rounds of upgrades for a single piece of equipment.