Because colonialism caused major wars that drained the natural resources of every country, had it not been for colonialism causing the wars the natural resources would not be so depleted. Also colonialism caused it because the people who are driven by colonialism to dominate countries then countrie involved in the war would still have their resources.
No, natural resources are not endangered due to colonial rule, because people tend to take better care of the things that they own. If someone own a resource, they do not want to use it up. Colonial rule also established property rights in many places, which went a long ways to preserving these resources rather than exploit them.
Natural resources started being consumed at a faster and faster rate since the Industrial Revolution when technology and production began to quickly increase. The Industrial Revolution began in the mid-1800's when colonial rule was ended or ending in many areas, and technological advancements have increased even more post-colonial rule, resulting in increased resource distribution and consumption.