The faster the price discovery, the shorter the validity time. This means a more accurate price.
> If a few milliseconds can change the value of a financial instrument then we have to accept that waiting a second or two will allow a lot more traders to reevaluate and offer a fair price.
You're making the mistake of assuming the price is static. If I have to quote you a price on an instrument that's valid for the next 5s, I have to be more conservative than if I'm quoting for the next 5ms. Which means you get a worse price.
> The HF in HFT looks like a play to reduce the number of traders who can act on information, which means the buyer/seller is probably getting scalped. HFT traders are making money arbitraging the speed of information dissemination, which indicates that other traders would offer different (/better) prices if the market waited a half-second or so to let everyone gather all the relevant data.
There's literally nothing stopping or limiting the numbers of players operating at this speed. What the race actually results in is all market participants getting smaller spreads and better prices.