One reason powerful nations rushed to grab colonies in the 1800s was the desire for raw materials and natural resources.
By the 1800s, strong, centrally governed nations/states in Europe had emerged. The industrial revolution that began during this time greatly enriched the European economies.
The industrial revolution created needs and desires that had to be met. The European nations, aided by their new economic and military strength, resorted to seize foreign lands to exploit them for raw materials and resources to feed the mother industries back home.