[xixi77]

All intermediaries -- be it floor traders, or HFT's -- earn money from the same source: the difference between prices that actual investors buy and sell stocks at (lower difference is also referred to as higher liquidity).

Now, the resources that were going to traditional specialists and a subset of the professional traders, are going to HFT's, with some of that returning to investors in form of lower trading costs (if we buy the argument that liquidity has indeed improved, of course. Most of what I've seen indicates that it has.) As a side effect, we have technology improvement, useful for other things.

Now, there can be an argument made against HFT's, and in favor of more traditional traders, related to a potential decline in market depth. So far, I have not seen any convincing proof of this being the case, but I am open to it.

However, I think a lot of people arguing against HFT's do not quite understand that their position is literally that we need to enact legislation in order to protect Wall Street from competition :)