Why is it sometimes difficult to make decisions involving economic development and the environment?

More often than not it is very hard to make decisions about economic development and the environment and manage to balance them so that both of them are in the desired position. The problem is that almost always the economic development depends on destroying parts of the environment, so often the choice is to either to stagnate on an economical basis and protect the environment, or push for economic development and destroy parts of the environment. This is very often a conflict situation, and in the last decades with the bigger awareness about the nature it is becoming even harder a decision to be made.