The Qur'aan says that the wasters are the brothers of the shayaateen.

Answer

Spending unnecessarily is waste. If something is needed, then regardless of it being expensive, it will not be waste to buy it. Looking at the huge sums of money Muslims are squandering on nafsaaniyat and shaitaaniyat, on merrymaking holidays, mock ‗umrahs', mock i'tikaaf in Musjidul Aqsa, haraam wedding expenditure for show and pride, constructing mansions out of pride, women wasting money on garments which are not needed and which excessively clutter their wardrobes, and which they wear to showoff, spending on fashion clothes, etc., etc. are such waste which transforms the human being into a shaitaan, hence the Qur'aan Majeed states: ―The wasters are the brothers of the devils, and shaitaan unto His Rabb was ungrateful.‖ All these wasters are in reality most ungrateful for the Ni'maat (bounties) of Allah Ta'ala.