Earlier quoted context omitted.
You have no idea how to actually write an informational comment rather than hinting at some received wisdom and greater general understanding without actually revealing any of it, wrapped in condescension which actually lands far of the mark and fails to address the points raised here, do you?
Fine, I'll attempt to parse through your example. "Rather than buying Wigets-R-Us at $100/share, the HFT slips in with a, say, $99.99 offer to the seller, and offers you $100.01." So, 2 possibilities, you don't say, but you are sending a limit order to buy at $100 or a market (or marketable limit, or fill-and-kill) order to buy at $100. Apparently, you seem to be suggesting that there is a seller in the market, presu…
HFTs pay brokers for order flow so they get orders before they hit the exchange and decide to trade on them from their own book (at NBBO) or pass them on to the exchange. Besides jumping the order book at the exchange they get advance information on orders about to hit the market.