What do you even do with caps?

I mean, outside of a few very expensive items, I have almost never left a vendor owing more than a few hundred caps tops. Just dumping unneeded ammo calibers and valuable loot always brings me well into the positive on any trade. Typically I have to visit multiple vendors because they dont have enough caps or stimpacks to trade off all my loot.

I don't really care about settlement building but even on playthroughs where I do its rare that I need to purchase supplies. In fact it kind of ruins the game for me sometimes because after a while, many of the things I would have previously collected like cigarettes become not even worth the weight and it takes much of the fun out of looting.

Also, I dont have enough free time to play survival but I know they become significantly more important there since you can't carry nearly as many supplies. I'm referring to the regular game.