In Deuteronomy 17:14-20, Moses gives the Israelites guidelines on choosing a king:
When thou art come unto the land which the LORD thy God giveth thee, and shalt possess it, and shalt dwell therein, and shalt say, I will set a king over me, like as all the nations that are about me; Thou shalt in any wise set him king over thee, whom the LORD thy God shall choose: one from among thy brethren shalt thou set king over thee: thou mayest not set a stranger over thee, which is not thy brother. But he shall not multiply horses to himself, nor cause the people to return to Egypt, to the end that he should multiply horses: forasmuch as the LORD hath said unto you, Ye shall henceforth return no more that way. Neither shall he multiply wives to himself, that his heart turn not away: neither shall he greatly multiply to himself silver and gold.
And it shall be, when he sitteth upon the throne of his kingdom, that he shall write him a copy of this law in a book out of that which is before the priests the Levites: And it shall be with him, and he shall read therein all the days of his life: that he may learn to fear the LORD his God, to keep all the words of this law and these statutes, to do them: That his heart be not lifted up above his brethren, and that he turn not aside from the commandment, to the right hand, or to the left: to the end that he may prolong his days in his kingdom, he, and his children, in the midst of Israel.
Later on, during the latter years of King Solomon:
1 Kings 10:14-17, 21, 26-29; 11:1-8
Now the weight of gold that came to Solomon in one year was six hundred threescore and six talents of gold, Beside that he had of the merchantmen, and of the traffick of the spice merchants, and of all the kings of Arabia, and of the governors of the country. And king Solomon made two hundred targets of beaten gold: six hundred shekels of gold went to one target. And he made three hundred shields of beaten gold; three pound of gold went to one shield: and the king put them in the house of the forest of Lebanon. And all king Solomon's drinking vessels were of gold, and all the vessels of the house of the forest of Lebanon were of pure gold; none were of silver: it was nothing accounted of in the days of Solomon.
And Solomon gathered together chariots and horsemen: and he had a thousand and four hundred chariots, and twelve thousand horsemen, whom he bestowed in the cities for chariots, and with the king at Jerusalem. And the king made silver to be in Jerusalem as stones, and cedars made he to be as the sycomore trees that are in the vale, for abundance. And Solomon had horses brought out of Egypt, and linen yarn: the king's merchants received the linen yarn at a price. And a chariot came up and went out of Egypt for six hundred shekels of silver, and an horse for an hundred and fifty: and so for all the kings of the Hittites, and for the kings of Syria, did they bring them out by their means.
But king Solomon loved many strange women, together with the daughter of Pharaoh, women of the Moabites, Ammonites, Edomites, Zidonians, and Hittites; Of the nations concerning which the LORD said unto the children of Israel, Ye shall not go in to them, neither shall they come in unto you: forsurely they will turn away your heart after their gods: Solomon clave unto these in love. And he had seven hundred wives, princesses, and three hundred concubines: and his wives turned away his heart. For it came to pass, when Solomon was old, that his wives turned away his heart after other gods: and his heart was not perfect with the LORD his God, as was the heart of David his father. For Solomon went after Ashtoreth the goddess of the Zidonians, and after Milcom the abomination of the Ammonites. And Solomon did evil in the sight of the LORD, and went not fully after the LORD, as did David his father. Then did Solomon build an high place for Chemosh, the abomination of Moab, in the hill that is before Jerusalem, and for Molech, the abomination of the children of Ammon. And likewise did he for all his strange wives, which burnt incense and sacrificed unto their gods.
Accumulating great quantities of gold and silver? Check. Multiplying horses and sending Israelites to buy them from Egypt? Check. Having a massive harem of at least 700 wives and 300 concubines (maybe more) who turn his heart away from God? Check.
Who can tell how much better Solomon's reign would have turned out if he had only spent more time with a personal copy of the Law at his side and studied it each day...