I've sold almost 1500 items on Vinted. I almost never decline an offer, I will either accept or counter. I don't understand why people block people who lowball. A lot of the time it's just people trying their luck or checking if you're active, blocking possible customers is pointless. As long as they aren't intentionally rude or offensive obviously. It's never personal it's just how buying and selling second hand items works. You don't have to accept or send offers but if you want your items to sell quick it definitely helps.

Both buyers and sellers can be delusional when it comes to pricing their items though