You just need one unfortunate bad trade in selling straddle/strangle to destroy your life. Conversely, you just need one fortunate good trade in other options strategy to retire immediately.
IF I am not mistsken,he is not taking overnight risk which is huge.. SPY/Spx is liquid enough where he should easily be filled on a market order without ignoring slippage.. Obviously, if you are a decent directional trader,Long 1 side of the 0 -1 day is a better trade..
Yes if someone has good directional strategy can add more return with open delta. But will have more mtm swings also.
I do delta neutral straddle on spx and nq 0dte options, i set stops around 30% with trailing based on atr. doing it since june and so far got returns around 2-3% per month.