I think it is always easier for a sizeable group of people to blame a secret conspiracy for their troubles, in lieu of taking responsibility for their own lot in life, regardless of whether that conspiracy is made up of Jews, the Illuminati, the CIA, International Bankers, Jesuits, the Masons or the Bush Family.
What makes conspiracy theories so appealing is their ability to clarify events that have a high level of complexity. It can be very difficult to figure out why a region or industry is suffering economic hardship. It is easy to say "the powers that be" are the ones creating the problem.
The oil industry has long been accused of conspiring to suppress alternative energy sources. There is no conspiracy in the fact that oil is one of the cheapest and most versatile forms of energy we can find on the planet.
Conspiracy theories also help satisfy people’s craving for melodrama. The villains in conspiracy organizations are often given mythical powers, because, as everyone knows, the most alluring foe is one that is the most threatening.
The danger in conspiracy theories exists when people allow facts to become oversimplified to the point at which they lose contact with reality. The folks who are prone to believing every evil plot that comes along have the common trait of basing truth on how interesting the conspiracy sounds.
Unfortunately, sometimes, as with the Jews, those doing the oversimplification sometimes gain power, be it German in the 40s, Spain during the Inquisition or most of the MidEast today.