So property ownership is protected as long as you don't feel you need it?

In practise, yes. Monopolising the only water source in town will get your property seized by the majority right quick; why should the legal system pretend otherwise?

No. This isn’t “as long as you feel you need it”. This is the seller abusing its position to demand the buyer to buy its own product.

If someone punch me first, I’ll punch back. It doesn’t mean that I think it’s okay to punch people in general, but sometimes it’s warranted.