I think it relates to the other, similar old saying, "The love of money is the root of all evil." The truth in that statement has been illustrated in real life every day since the time before it was uttered, and all the way to our time today. And it definitely just keeps getting worse.
Greed ruins everything IMO, and greed is what has us where we are today more than anything else. Greed for riches and greed for power, and the greediest Mofos on earth are the ones making things shitty for the rest of us.