Earlier quoted context omitted.
We know, empirically, that a lack of liquidity increases trading costs, which in turn is directly channeled to the prices of goods and services that rely on this liquidity (more or less everything in the world, even more indirectly ones like education). It's difficult to say 'things would be X% more expensive' because of the interconnected complexity the GP was talking about, but there is definitely a very apparent b…
I think the question is at what point does liquidity have diminishing returns? If a security could only be traded once per 10 years then it's obvious that its lack of liquidity would make it less valuable. Holding it would tie up your capital quite significantly. However, if you had a turn-based market where every trade got cleared at the top of the minute it's not clear to me at all whether that would effectively be…
Once you disregard the rapid transactions that do not have a significant effect on the price, your average human investor is probably putting down some fill-or-kills or limit orders and actually benefits from HF liquidity trading.
It's hard for me to understand, let alone explain, why milliseconds would matter for the human investor, but I what I can tell you is that GS is not investing 100M USD just for buying derivatives every other minute.