Greed is often driven by an even baser emotion; fear.
You have plenty of money, food, travel, gadgets, whatever, but you want to hoard more and more because you fear it could all be gone tomorrow. Or you fear that those who (apparently) have more than you will be more popular, or will get better treatment.

The bizarre thing that happens to many people though, is they take risks to get what they want quickly, which increases their fear of loss (of materials or status), which drives them into greed.

I have seen multiple examples of people in the crypto-currency space taking risks with their hard earned money on some fake moon-coin. It may work a few times but in the end they mess up and are heartbroken.