Too Much Money- Too Much Free Time
The Gemara in מסכת ברכות describes how Moshe Rabbeinu convinced Hashem to forgive the Jewish people for the sin of the Golden Calf.
Surprisingly, Moshe blames Hashem for the sin. He says that the fault was with Hashem because of all the gold they were given when they left Egypt. Without gold, they could not have built the Golden Calf.
The comparison to this was like giving a young man a pouch of gold and placing him in front of a house of prostitution. There is just too much temptation to resist.
This story seems to also explain the problem with the Western world today. When there is an abundance of money and free time, it only spells trouble. If the funds were not there and people used their time wisely, they would not have time to sin.
This is why the Mishna says יפה תלמוד תורה עם דרך ארץ, that Torah and work is ideal, for the involvement in both will minimize sin.