QQQ can go down 20% and I do not account for that possibility in my calculations. It took some time to make calculations assuming QQQ stayed flat which is an extreme assumption. While a 20% downturn is realistic, it’s not something you can calculate since no one knows what will happen to the stock market tomorrow. Same for appreciation.
I did allow for some strike price wiggle room and explained that you can set a further out of the money strike price to decrease the chance of the option getting exercised. My logic is that you should only do covered calls and cash secured puts for stocks and ETFs you wouldn’t mind holding, so if you have no problem owning QQQ shares over the long term you should be able to emotionally weather something like a 20% drop if you stay focused on the big picture.