As a trader running a black box system you don't care about the value [of the stock you are trading], you care about how much money you can make in the next few seconds. And if your trading causes the share price to fall from $40 down to 10 cents, you don't care, you made some money along the way.
Anybody who's now making money from HFT, whether it's exchanges, or banks, or whoever; they will all be saying "Oh, don't worry, don't worry". And they'll be looking at their watches and thinking "I just have to keep saying don't worry for another two years, because in two years I will have made all the money I need to make and the opportunity will be gone". So, I'll just keep saying there's nothing to worry about and keep an eye on my watch.
The following animated GIF chronicles the rise of the HFT Algo Machines from January 2007 through January 2012.