For clarification you write puts at or out of the money. If executed, the premium earnt offsets the difference between strike price and spot price. No one is saying this guarantees against a market crashes but it acts as a cushion. You are still trading when you decide not to place a trade.

To put it another way, you make money when you buy, not when you sell. Therefore your purchase price is a margin of safety if done right. I carefully select the companies I trade by building up a 'conservative' price target based on a company's tangible book value per share (TBVPS). I try to write puts that offer a good risk/reward profile relative to the TBVPS. Even if I was caught in a market crash I'm as close to book value as I can get. Having done my homework I'm sure this company will outlast the extreme market sentiment. When such events occur I add to my position on the strength of my fundamental analysis. The market always overshoots and creates a wealth transfer opportunity.