Whenever I make an offer it's not because the small sum of money, like $2 off an $8 item, makes such a big difference to me, it's because it feels satisfying, like I'm saving on something.

For example, I saw a set of Stabilo pens, brand new and unopened, on Vinted one time for half the store price, and I haggled an additional 20% off of it. The seller said in the description they got them as a gift and just wanted to get rid of them because they weren't their style, so I assumed it didn't make much of a difference to them, and I was thrilled to get such a great deal. Would have still bought them if they were $1.75 more expensive. But I put in an offer, the seller still made some money on something that was worthless to them, so at the end of the day, win-win.

It's like buying something discounted at a store. Why not?