It's a fairly distinctive contrail pattern, with two of the trails on the pilot's right side merging together, and the trails starting fully behind the engine. So I just searched for "contrail", and it only took a few minutes. When people want to fake a photo they often seem to Google the source images, which makes it easier to debunk.
I'm not 100% sure it's the correct underlaying image, as the pendule patter does not match exactly, but it's hard to tell with with blur.
People like to fake things, I guess some of them want the attention. But maybe some of them think they saw something and are drawing what they saw, and later it gets passed off as genuine.