Bigger is not necessarily better, especially as regards nations. In the business world, using the Boston Consulting Group matrix, a company or corporation might aid its growth and power by purchasing other select companies to add to its portfolio. Later, it might divest and choose to sell its “dogs” and even “cash cows” when they approach becoming clear liabilities. All this is done to please shareholders.
The practice does not fit the world of nations, especially as regards the “big three”: the US, China and Russia. The world of people is not the same as the zero-sum game of business.