The book of John is often called the book of ‘signs’. In chapters 2-12 John gives seven signs. These signs are intended to reveal to the people that Jesus is the promised one, the Messiah. In John chapter six we read about the sign of the feeding of the 5,000. The bread of life discourse follows this sign. The sign was intended to lead the people to put their trust in Jesus. The effect, however, was predominantly a desire for more food, not Jesus. When someone comes to Jesus there are many benefits gained (sins forgiven, eternal life with God in heaven, etc.), but they are just that, benefits. They are not the main thing. Jesus is.
Sadly, many times Christians (myself included) treat Jesus like the people in this passage. We want what Jesus can do for us, but we aren’t too bothered about wanting him. The Christian life and the gospel is not, principally, about what Jesus can do for us (as if you could separate his work from his person), but it is the glory that Jesus offers himself to us. To clarify, the gospel IS what Jesus has done for us, but we cannot separate from his person what he has done and offers to us, which is what so often happens. We come to him and have him! He is our treasure, not what he does for us. He is our joy, not what he gives us. He is our everything. As the hymnist writes, ‘You can have this whole world, but give me Jesus’.