Lack can breed misdeeds as well.
I once heard someone say: "The (lack) of money is the root of all evil."
The reason why crime is higher in poor neighborhoods is because more people feel desperate about their circumstances.
Greed is usually associated with those people who have enough or more than enough to be comfortable but (mentally) they still feel what they have is "not enough". Maybe they've held onto the memories of being poor for so long that even their present reality of wealth does not offer them insurance.
In other instances some of them see how much more others have. This drives them to sometimes do whatever it takes to catch up or surpass others. They have to be "king of the hill" or "top dog".
Imagine being full from eating a meal but you insist on continuing to eat because food remains on the table. You don't want others to have it. In many ways I would say greed is a mental illness of sorts.