People use the bartering option in Fallout wrong. The bartering option is a math minigame, you want to have something you exchange something of value you have for that, its called Bartering not comerce, the caps come when the values dont match in trading so like:"i give you afew granades i have and this pistol if you give me 3 stimpaks and this bandage pack" "deal, but since i think these are abit much and you dont have anything cheaper to trade, here is this 3 caps" "good". Thats why nobody is rich on Caps in Fallout. All of Fallout economy is based on battering, caps exist when you dont have stuff to batter with like:"hey i got nothing but i can give 20 caps for those stimpaks" "fine, i take it. Here it is" and "i give you this, this and that if you give me caps" "you are weird but sure".
Wealth in the wasteland is:
A wasteland trader with: 300 caps, no antibiotics, no ammo and no food …is poorer than a farmer with: corn, purified water, two rifles, zero caps.
Its why bartering perks are in Charisma in the first place and not Luck, because if it was Comerce then the skill would be luck or Intelligence in business