The Webster-Merriam dictionary defines materialism as "a preoccupation with...material rather than intellectual or spiritual things."
As the story begins, we find that Crusoe is an impulsive young man, not intellectually or spiritually centered. Crusoe's father is rich enough to provide for his family, as well as to educate his son so that he might be a lawyer one day. "Things" come easily to Robinson, and as is the case with so many of us, he has no concept of what is truly valuable until he has nothing.
Crusoe feels driven to go to sea. Although everyone he knows tries to deter him, he will not be stopped. So Crusoe goes to sea. He barely survives the ship's destruction in a storm--but once he reaches land, even though advised again not to, Crusoe cannot resist the siren call of the sea.
This trip is also a disaster: the ship is captured by pirates. Crusoe is enslaved for two years. When he escapes, he eventually buys a plantation and is very successful.
One example of Crusoe's materialism can be seen when he is approached by men who want to capture black slaves to work their plantations, something they may not openly do. Crusoe agrees in order to make more money, and takes to the sea. When a storm strikes this time, the ship and companions are lost, and he is stranded alone on an island.
At first, Crusoe must make do with what he can salvage from the ship's wreckage and what the island offers. His priorities change; finding gold in the shipwreck, he notes that it is useless; he doesn't care if he keeps it or leaves it. What is important are the things he needs to survive.
For more than twenty-five years Crusoe carves out an existence on the island. He builds a "home," and finds ways to plant crops and raise livestock. In the face of adversity, he learns the value of what he has worked so hard to achieve. At one point while exploring, he is panicked when he thinks he will lose his new home. He thanks God when he returns safely. The value of his possessions comes from how they enable him to survive physically--and mentally, not from any financial consideration,
Even as he feels that God has blessed him, showing spiritual growth, when Crusoe finds a human footprint in the sand, his faith is tested. Whereas his greatest affliction has been living without human companionship, now he is terrified because he doesn't know what kind of human it might be. With time, Crusoe's good reason takes over: he believes he is where God wants him and decides to accept whatever God wants for him.
Eventually, Crusoe rescues a native, naming him "Friday." Whereas Crusoe ended up on the island while trying to steal natives and make them slaves, Crusoe and Friday ultimately become friends, enjoying each other's company. Friday decides he'd rather be killed than go home, and Crusoe is happy that he stays.
Crusoe still makes impulsive decisions, but now reconsiders and lets his moral compass lead him. For example, when the cannibals return to the island, at first Crusoe wants to kill them, but stops to ponder the morality of such an action. Seeing that one victim is a "Christian," he finally decides it is right to attack and save the man.
When Crusoe finally leaves the island, he returns to those who helped him in the past. Feeling indebted, giving them his money is of little importance to him.
Crusoe, once only concerned with himself, has become a thoughtful and spiritual man, better for the calamities that have befallen him.