If you like good conspiracy theories try this one for size. The world economic collapse was brought about deliberately by political force in the face of overwhelming concern about the environment. With the trend in climate change much closer to the tipping point than previously admitted, 'the powers that be' had to take a radical and dramatic step to stop consumerism from exacerbating the problem.
With the rich and powerful secure in their bubble and able to take advantage of any downturn by buying and consolidating assets on the cheap, it was considered the right time to put the brake on, bringing, at a stroke, consumer spending to a halt, a cut in energy consumption and much reduced air travel.
It's the Bowling Ball Theory. If you go into any mall, shop, or commercial district and could roll a bowling ball without hitting anyone, no one is out spending - the plan has worked. What could never be done by consensual politics has been achieved by a machiavellian strike.