what is the reason for this?
most would probably say the banks. The crashing of banks was the most obvious phenomenon that can be related to and seemingly cause the global downturn that has followed. But how much are banks responsible for revenue, for productivity? not much.
banks are run by the rich and the intelligent they have a jolly good time and make lots of money moving it around but they really arent producing anything. It is the factory worker, the mechanic, the waiter who are the foundations of an economy. The shittier the job the more it contributes to the nations gdp.
The intelligent and the wealthy are either given the means or come to understand that despite the importance of these unpleasant jobs they are best avoided and that personal satisfaction and wealth go hand in hand.
but as time goes on the rich become poorer and the poor become richer. the working class no longer want to work the shitty jobs they have evolved beyond it. It has fallen to an underclass drafted in from other countries the west is also propped up by developing countries and their productivity. Ultimately productivity has fallen and the recession is caused by the evolution of the poor. They gain access to technology and more wealth and no longer want to endure the struggle and turpitude of their parents.
This ofc is an ongoing process. people gave up the farms and the ploughs and went to the factories. then they left the factories and went to the offices. now people sit on their arses at their computers playing computer games perhaps doing casual part time jobs. The economy will recover but only when work for the masses becomes more amenable and this will happen through more and more of the economy being based on the internet which is more pleasant than the horrors of office work.