The massive corruption common in so many developing countries would be quite impossible if Western countries did not provide convenient opportunities to ship ill-gotten funds out of the country. It wouldn't make much sense for a ruler to store in his basement large quantities of stolen cash in his own country's currency. A corrupt ruler wants to be able to keep this money safe and to be able to spend it. And for this, he needs to convert it into a Western currency and store it in a bank abroad, where it can also earn investment returns and be bequeathed to his heirs.