Finance may be man-made. But 200 years ago for a rich country to obtain a poor country's natural resources they had to invade an army and add it to their empir

Finance may be man-made. But 200 years ago for a rich country to obtain a poor country's natural resources they had to invade an army and add it to their empire; while in the modern age, the rich country can swap the natural resources for pieces of paper they can print at will. Why bother to invade under such circumstances?