[Sniperfish]

Thus assuming that someone else will always pay the spread. Tragedy of the commons ensues.

But this whole article seems to be written for retail investors. And as much as HFTs may sound scary for retail traders they make their money off institutional trading. So the larger impact to retail flow is from the response Institutional desks are forced to take to ensure they are not disadvantaged by HFTs, which then affects how institutional and retail flows are able to interact.

Ultimately a 1000 APPL.US order will get filled and who pays the $0.01 spread is largely academic as it is an inconsequentially small part of the total settlement $ paid.