It performed exactly as I intended to under normal market conditions. It isn't intended to do that under a Black Swan event.
Okay, so what are you going to do under a black swan event then when those options turn into 5-10x losers vs what you originally envisioned?
If the answer is "keep my size reasonable so that under 'worst case' scenarios" it wouldn't wipe out more than 5% of my account" then wrong answer. There's no way to do that AND make a high return at safe levels of risk whilst using this strategy or in other words there is literally no way you'll get anything close to 30% a year and suffer only a 5% drawdown in "adverse selection" cases using a "premium selling" strategy like this.
I just pulled up the Sep'16 chain for ES and as an example 1600 puts (3.8 delta, 1.0 vega, 32% IV) are 6.25/6.75 right now. Let's say you sold two of these every quarter for a year straight (you can't sell more frequently and still hold until expiration either because that means you're now "over-leveraged"), you'd be up a whopping 2600$ - meaning on a 10k account (which would be nuts), it's a 26% gain in the take-it-to-expiration, never ITM, absolute best simple case.
Now let's say you start the new year off on the wrong foot where one of those 300$ "premium selling never loses" specials goes to 50 bid after Pyongyang nukes Seoul on a Saturday night, leaving you with a 5000$ boat anchor, you're out 4400$ - completely killing 10 months worth of "trading" and converting your shiny 12600$ account to a new 8.2k account or a 35% loss in one friggin' trade. Who the heck would want to trade in such a way that they work hard on something all year and then one single event erases all of that (and more)?
Still think "Karen was over-leveraging" ? No - it's this simple, the things you are trading have incredible risk embedded in them. People want to ignore that risk because they're too attracted to a "sure thing / never be wrong" mentality and downplay all the people telling them the trades are dangerous. They come up with fancy "risk control" methods like GTC stop orders, ridiculously OTM "insurance" options, and other games to give themselves a false sense of security. Then the day happens, they get smoked, 25-50% drawdown if lucky, way way worse if not lucky (as in you owe your broker money).
While the examples I gave for outlier events may sound extreme, so does 12 months of absolutely perfect trading with no losses whatsoever. Translation: you will not earn 30% a year without completely risking your ass here.