This exchange meeting can be simply understood as several major powers asking for money while those willing to give it keep coming incessantly!
The reason everyone is willing to invest is partly because these powers have decent reputations.
In the base, reputation is very important, the larger the power, the more they care about their reputation, and they put a lot of effort into maintaining it. So, many people think their credibility is relatively high.
Another reason is, many people also understand that they can just treat it as a straightforward investment.
Since it's an investment, it naturally involves risks, but as long as they believe the benefits outweigh the risks, it's worth investing in.
Plus, investing money without sacrificing manpower has its benefits too, at least they keep their lives regardless of winning or losing…