[vostok]

The fact that computers are committing multiple trades in a fraction of second to make tiny profits does not mean that they are screwing you out of every 10th of a cent. In fact, my intuition is that you would be worse off without them because whoever you're trading with would be making big profits rather than tiny profits. It's the competition between computers that makes that profit so small.

> It is a statistical certainty that a percentage of trades will be losers. You are establishing a position with an unknown outcome. Sometimes they go your way, other times they go against you.

> How is it possible that one of the largest high-frequency trading firms executes millions and millions of orders for four years without ever having a down day? The short answer is what they do is not trading -- it is skimming. I call it legalized theft. High-frequency trading is a tax on investors, encouraged by the exchanges, allowed by the SEC. It is prima facie proof that something is amiss.

It seems to me that this author has difficulty with taking the limit of 1/sqrt(n) as n grows without bound.