With regard to the Bretton Woods System, the AIIB has gotten sign off from European allies despite the US's efforts to keep the AIIB underwater. Paired with the BRICS bank and Asean trade deals the IMF and World Bank are being seriously challenged in their ability to make strategic infrastructure investments. If you would like an example of what that looks like: the AIIB is investing hundreds of billions of dollars in Pakistan and more broadly Eurasia to build out oil pipelines and trade routes - a land route in Eurasia to pair with South China Sea and Indian Sea trade routes for China's "new silk road". Please feel encouraged to ask more questions.
I happen to agree with the West's national security posture that their status is hollowing and that the AIIB and other institutions propose viable alternatives for large portions of the world and threaten the old order (though I'm no expert either).
The reason is that foreign investment is a way that countries can use to very strongly project power. Take the activity in the Baltics - the IMF packages to Kiev - to influence political and geostrategic outcomes which is often worth huge amounts of wealth in the long run. That is to say you aren't always going to get money from the country you are lending to, but you will get influence on political outcomes. And we can see that with China's plans in Eurasia and how these plans for example align with their veto votes on UN activity in the Middle East. Russia had tried to create a Eurasian Union, which has kind of staled but it's likely that with a giant investment bank to fund infrastructure that it can be pulled off.
Long argument short - it's not always about getting money back on your loan: it's often about getting your pipeline, your highway, your port, or your defense garrison.