>Researchers Svetlana Bryzgalova, Anna Pavlova, and Taisiya Sikorskaya found that retail options investors lost over $1 billion during a bull market from November 2019 to June 2021. Their calculations don’t include their estimated $4.13 billion spent on the trading costs, i.e. wide bid-ask spreads that incur immediate losses for options traders. And lastly, we can’t forget the $800 million burned in that time period on commissions.
Wide bid-ask spreads are a trading cost? That incurs an immediate loss? That's independent of the loss quoted in the return? If you (for some reason) do your options trading by only accepting standing bids/asks (market orders), then yes, you get a bad price ... but that would be rolled into the return figures, not an independent loss.
No matter what the bid/ask spread, you can place an order in the middle and wait for a fill.
And commissions aren't a "trading cost" but something that goes in a different (non-trading-cost) bucket?