When I buy something [car, bread, blanket, medication], I buy the promise made by the seller.
When you buy something, you are buying the trust that whatever you are buying will meet your expectation.
You are buying trust that the car will transport you peacefully, the bread will be delicious, the blanket will make you warm, and the medication will make the pain go away.
Buying is defined as the acquisition of one thing in exchange for something else. Of course it goes beyond ownership or the trading of things.
Buying is an exchange of trust and value, a belief in promises we expect will be kept.
Selling is described as the transfer of goods or services in exchange for money. Of course it is much more than this.
Selling is an exchange of trust and value, a set of promises we intend to keep.
What we are really trading in is promises, assurances upon which expectations are based, which means that our intention is a big part of what we sell.
People buy from people they trust.