The hfts HAVE to give you at least as good execution as is available on the market, and if they trade while they are holding your order your order can’t execute

The hfts HAVE to give you at least as good execution as is available on the market, and if they trade while they are holding your order your order can’t execute at a worse price than their trades (Manning rule). HFTs like retail orders because they don’t move the market, so you can collect some of the spread without worrying about getting run over by an informed institutional player.