Ask any good salesman the key to making a sale, and they will tell you that there are two parts to a successful sales pitch. The first step is to create or highlight a problem in the mind of the customer. The second step is to provide a “logical” solution to the problem, thus dissipating any anxiety.
The key to the solution being accepted is that the customer has to feel some degree of trust in the salesperson, which makes it easier for the customer to believe that what is being offered will work. Once that happens, the belief becomes an integral part of their identity, so it becomes very difficult to dismiss it.
It’s pretty basic stuff, but it works most of the time.