In "Shooting an Elephant," why did George Orwell feel that he "would have to shoot the elephant after all"?

Orwell discovers through this scenario the intense irony
of imperial power. As he puts it, by turning tyrant, the white man destroys only "his
own freedom." When he approaches the elephant, Orwell is determined not to shoot it.
What makes him realise that he will have to shoot it is the crowd that has gathered to
watch the show and who expect the elephant to be
killed:

But
at that moment I glanced round at the crowd that had followed me. It was an immense
crowd, two thousand at the least and growing every minute. It blocked the road fro a
long distance on either side. I looked at the sea of yellow faces above the garish
clothes--faces all happy and excited over this bit of fun, all certain that the elephant
was giong to be shot.

Orwell
realises at this moment, as he sees these expectant faces looking at him as if he were
"a conjuror about to do a trick," that if he did not kill the elephant, he would look
ridiculous, which is what the whole imperial endeavour tried to avoid at all times. He
feels the "two thousand wills" of the people watching "pressing him forward," urging him
to kill the elephant. As such the slaughter of the elephant becomes an eloquent symbol
of the futility of the colonial endeavour.