The Vilna Gaon on Megillas Esther (3, 13) writes that there are three mitzvos performed on the day of Purim - the reading of the Megilla, Mishloach Manos to complement the Seudah and Matanas L'evyonim - corresponding to the three components that comprise a person. The reading of the Megillah corresponds to his neshama, the Mishloach Manos to his body and Matanos L'evyonim to his material acquisitions. It is evident from this explanation that one's money and possessions are part and parcel of who he is. If so, we can understand the spiritual ascension of Me'aras Ha'Machpeila after it was purchased by Avraham. It had been an essential part of Efron and now it became an essential part of Avraham, the greatest person alive at the time.
Rav Wolbe elaborates that we tend to believe that we are in control of our money and we may do with it as we see fit. However, this is not a correct perception. Every dollar and every material acquisition was Heavenly ordained that it be placed in a person's possession, and he becomes a guardian of all that he owns. Therefore, he must appropriate his money properly and not act negligently with regard to his belongings. One who constantly spends his money on frivolities might very well be lacking in his emunah. Such a person shows that he does not believe that his money was given to him by Hashem with a specific purpose in mind.
The Torah relates a number of stories, which according to Chazal, demonstrate this idea. One such example is when Yaakov Avinu prepared his family in anticipation of their meeting with Eisav, and he crossed over a river with his family and all his belongings. However, he forgot some small vessels and he put himself in danger by going back to retrieve them. Yaakov acknowledged the fact that his money was G-d given and therefore, spent time and effort to retrieve seemingly trivial utensils.
All possessions are given to a person for a purpose. If he doesn't need it himself, then it was given to him to allocate to others who do need it. Just because one may have no use for an item, this does not permit him to act carelessly with it. One who shows care for his possessions has in effect displayed his emunah that the Creator gave him those belongings for a specific reason.