When Orwell felt that he "would have to shoot the elephant after all" -- what did this teach him about the "real nature" of imperialism?in...

In my opinion, what this taught Orwell is that the people
who are supposedly in control in an imperial system (the colonizers) are not truly in
control.  They are often forced to do things that they do not think are a good idea or
even things that they do not think are morally right.  They have to do these things
simply to maintain their image and their ability to seem to be in
control.

Orwell feared that the natives would think he was
weak if he did not shoot the elephant.  If they thought he was weak, he and all English
would look bad.  This would make it harder for them to control their native
subjects.

So the point is that when you start to
imperialize, you are no longer able to act based on your own convictions and values. 
Instead, you have to act so as to keep your control over your
subjects.