Television preachers in the Word-Faith Movement seek to proclaim a prosperity gospel. A gospel where the faithful receive everything they desire because they have claimed it for themselves by faith in Christ.
However, the Gospel has never worked that way. The Gospel isn't a "name it and claim it" doctrine. The Gospel is about Jesus: His suffering, death, and resurrection. This is not about getting everything we want. It's about being faithful to His Word.
Luther contrasts the faith of Saul and David in 1 Samuel to show that having it all and being blessed by God are not necessarily synonymous.