Every trade that happens in every market in the world can be viewed from a game theory perspective as adversarial. In the absence of other outside factors each trade in isolation is a zero sum game, that is 1 counter party will make money on the trade while another loses (at least in the form of opportunity cost). In this adversarial encounter it is expected and encouraged for all counter parties to strive for unfair advantages. Some do this by using vast swaths of overworked and underpaid ivy league grads to do market research for them. Some do this by using massive amounts of leverage others do it by being fast, some use illegally obtained proprietary information and still others do it via mobbed up boiler rooms. Some of that unfair advantage we have deemed illegal and others we have deemed legal. The point is, the existence of an advantage in a trade is a necessary condition for the market to operate correctly, not evidence of it being rigged.

You will notice that the "big" players in HFT are much smaller than the people they are taking advantage of, the giant hedge funds. The HFT competitors have access to the same technology, technologists, exchange access and microwave networks. Further, they have better access to capital and legislative power, not to mention access to best selling authors.