Intimidation and fear push the natives to do what the invading country wants. Powerful countries steal the natural resources of the countries they control and use the natives as slaves. Depending on which side of imperialism you are on, it would change whether you considered it evil or not. Powerful countries would not see imperialism as evil, but as their right to impose their will and desires on less powerful countries. On the other hand, less powerful countries would see imperialism as evil. They would resent another country taking control and enslaving them and stealing from them