Nobody trades like this, and nobody traded like this in the early 2000s. That trading style has been obsolete for 20 years, and predates HFT. You don't see something, decide you want that, and then hit Enter or click your mouse button.
In this example, you decide the maximum price you want to pay in advance, and you enter a limit order. If you're selling you decide upon your minimum selling price, and in the same way you enter a limit order. You've locked in your profit, regardless of timing.
If you're setting up some sort of combination, you enter the triggering parameters in advance, and you don't even need to see what was being done on screen.
People say that computers are trading with each other. That is false. That's like saying that Microsoft Word writes documents. Trading companies, their traders, and their programmers write trading software and adjust parameters. 30 years ago, the "software" was held in the traders' minds, and the execution was done via outcry. The underlying mathematics is the same, and traders don't have to hold these calculations in their minds.
The problem here is this. Extremely rich companies can have the fastest links to the exchanges, but this is no different from the olden days where the oldest and richest companies had the smartest and most well-connected traders. The tools of the trade are slightly different, but rich and successful companies will leverage their money to be the most successful, or else they will be replaced by somebody else.
My own background is that I wrote a derivative trading system between 1999-2006 for a tiny company that ultimately didn't make it because we couldn't compete against the big boys. This angst about HFT is largely technophobia. The traders trade, they learn the software, and they often don't understand how it works. To programmers like me, the algorithms are a black box, but the traders do understand the mathematics pretty well. When you have traders coming out against HFT, you have traders who couldn't understand the software or were burned because their companies weren't rich enough.
People who have never worked in this field who are against HFT really don't understand computer-based trading very well, from either a programmer's perspective or a trader's perspective. Keep in mind that the job of a computer is to make mundane things happen more quickly, so we can focus on more human things. You want your 401K to execute as accurately-priced trades as possible. HFT ensures that both styles of trading benefit.