Thanks, but this is just anecdotal, like you said. It is easy to fool oneself; the mental accounting tends to forget or omit infrequent but small "outliers" e.g. from performance chasing when the market moves away. The fact that you made money as a MM with customer market orders does not imply that market orders are worse than limit orders for customers. In fact for equities with the U.S. market microstructure, I am quite sure based on evidence that small market orders have lower all-in trade cost than non-marketable limit orders in the long run average; and I think the U.S. equity options market is organized similar to the U.S. equities market. We're obviously only talking about time insensitive traders or investors who can afford "lazy" trading in the first place; if execution speed or volume are critical, market orders are a no brainer.
