Why don't I just let Vanguard, the most trusted firm in all of retail investing, explain that for me? Go look up with their Chief Investment Officer said about the impact HFT has on Vanguard's mutual funds.
Your reply reminds me of that saying, "Who do you believe, me or your lying eyes?"
If you can't explain it in pretty simple language why HFT-level liquidity is beneficial to society as a whole--to the people working in shops, managing restaurants, dealing in real estate, and on and on--then I'm inclined to think you're just trying to bluster about it.
That's a very self-righteous way of saying "I am not willing to perform a few Google searches and do a bit of reading".
Here, another hint: you can use the search box on the bottom of this page to find comments from me quoting Vanguard.
Either way, since you've accused me now of simply making things up to win arguments, I think I can let you off the hook. There's not much point in us discussing things further.
I won't speak for him, but I think I can sum up a position that he would agree with very simply:
HFT has made trading cheaper for the vast majority of market participants. It has done this at the expense of the previous regime that was less efficient and more squalid.
Further, don't take my (or his) word for it. Listen to Vanguard which has a sterling reputation for caring for the interests of their clients who tend to be long term, small scale, investors and large pension/retirement funds.
If you can't explain it in pretty simple language why HFT-level liquidity is beneficial to society as a whole--to the people working in shops, managing restaurants, dealing in real estate, and on and on--then I'm inclined to think you're just trying to bluster about it.