Every time an option pays off, my strategy would have worked. It becomes a question of time. If you start the strategy too much before the payoff, you will lose money.
Let me give you a simple example, one day the S&P 500 will drop by 20%. That is not an if, but a when. It will happen, sooner or later. If I buy SPY(an S&P etf) puts 5 weeks off at $645 every week for $5, then when it drops by 20%, I will have made more than $176 per share, so for five weeks $545. That means that as long as it happens in less than 109 weeks, I have made money.
That is an oversimplification, but it explains the basic idea. It is one of the simpler strategies for investing in options. Given that exact dates of moves are tough to estimate, it is a popular strategy.
The oversimplifications are that options contracts are for a 100 stocks, and I am buying more than one of them. The stock movement does not need to be exactly 20%, can be greater or lessor. If you are willing to sell and buy a little on the ups and downs, and there is some market volatility, you can make some money while you wait for the big payout.