One country's decline is a benefit to another one. It might sound cold and selfish but the truth is that if one economy is declining, you can use this to your advantage. If one country has a failing economy and they can no longer produce high quality products and their trade is losing significance then another country can sweep in and give better offers. This is simply the reality and so economy should not have emotions in because it will not do you good. If you want to improve your financial state, you have to compete. This is true even with smaller scale marketplace. Not a country's but let's say in one city. If one seller fails to deliver good products, you can sell better ones and take their customers. There is no space in the economy for soft hearted because everything is a competition. You have to compete for resources. You have to compete for demand. You have to compete for customers.
Economically the world is a global market. Just as businesses are competing for market share, nations also try to outsmart each other. The competition is so fierce that it could lead to attacks to sabotage economies. China became the second biggest economy because it took advantage of its population and technological development to take over the market share of many countries. With cheap labour and fast production speed China was able to produce cheap quality products. Many countries had to diversify into other areas while they depended on China for diverse products.
this china you talked about is one of the most smartest country i have ever seen in taken advantage or leveraging on other countries weakness. they offer help in giving out loan and cheap labor to country that cant manage there resources. after offering help to this country by given them loan, if they are unable to pay back, this country will give them their any asset in return as a pay back of loan and from their they begin to manage such resources in another country sending some population to such country to work and capitalize on such weakness. well i dont have any prove now to back up my claims but i know most of them occupying some company in my country and are dominating and producing cheap material to beat the price of goods in my country and they are beginning to make a lot of money from that.