I disagree. Most HFT is market making (passive trading with limit orders only), and they make most of their money from short-term and impatient traders, who account for most of the volume and repeatedly pay the spread. Long-term traders, by definition, don't trade very often so they're a small fraction of the total volume.

And its the market makers who provide the liquidity (with limit orders) for the long-term traders when they do decide to trade, not the short-term traders (who take liquidity with market orders).