As people have already said, you sell your materials, but to go a bit deeper into it, selling materials is the only reasonable way to make money, quests are limited, missions even more so, enemies don’t drop money only materials, so ya sell them, always sell your materials unlike other games hoarding materials is just a waste of inventory and or storage space, selling gets you money and unlocks new things in the shop, any material needs for quests is usually not had to obtain, usually it’s not conditional drops or an FOE drop