Another gentleman I spoke to proclaims the worst problem in the world to be greed.
Greed was considered one of the seven "deadly sins" in early Christianity, in the form of "Avarice." Avarice covered not only the excessive wish for money, wealth, and material things that we consider greed in the modern world, but also the desire to spend money pointlessly.
I can't tell you how many articles I've read recently by capitalism-fanboys proclaiming that greed is actually a good thing, since it drives the economy by making people work hard to fulfill their desires, but I think the truth is between the two.
Wanting to work hard to fulfill your desires seems to be a good thing, but it can easily go too far. Scamming people, stealing, and fraud are often driven by greed. Changing the balance of power to suit yourself is quite common in the corporate world, and it has gone on to an extent that the world starts to resemble Feudalism, with lords who control nearly everything commanding around serfs that control nearly nothing. The CEO of a company makes obscene millions while the people that make his company actually function earns but a few thousand, and are routinely fired to give the board yet another bonus.
No machine or chemical can help this, but Greed must be tempered by empathy and kindness to be of any good to society.