(I don't actually feel like I did anything wrong, though. Just bought low and sold high, around oil macro events that anyone else could have seen)
A trade is neither an expression of justice or injustice. It's just fucking numbers that we attach so much emotion and judgement on. Amoral != immoral.
We're nothing more than pond scum on the surface of the Earth. The Earth is full of stuff.
I don't actually know that it makes sense to judge these particular actions (especially of small players) in the face of the incentives, but I think your dismissal is too cavalier to be effective. The fact that your impact on the world is mediated by numbers doesn't itself absolve you of anything.
I'm not going to sit there and try and correlate VTI's price to ensure it's some kind of inverse to Lockheed Martin's performance, and I doubt anyone else is either.