|Martin Armstrong made some very good points a few days ago.|
The excessive amounts of global debt denominated mostly in USD means that overseas capital and other productive expenditures are reduced as more money is used to pay USD denominated debt. This slows down or severely impacts foreign economies, making local investments unpopular. Money flows to the US stock markets, which should continue to do well until a currency crisis hits.
The above is a severely shortened version of his thesis. The rest is here: