There you go again with "insertion." HFT market-makers don't thrust themselves between two people who are about to transact. Their orders were already in the market, and you came to them.

The "Flash Boys" case is a funny one. The HFTs did see the orders--but so did EVERYONE else, and in basically the same instant, because all transactions are publicly disseminated. Your point is right in a very narrow sense and very wrong on every axis that actually matters.

I'm mystified as to why Flash Boys didn't valorize high-frequency trading. It's a Moneyball story where the scrappy nerds use computers and math to out-compete the dinosaurs. Oh well.