Market makers mostly sell options, and the public buys?

I think the actual statistic is 80% of options held at expiration are worthless. But a large proportion of the outstanding options on any given option series are closed out before expiration.

 

emini wap-wap--- Were you selling puts last October and November???

 

I see you've read fooled by randomness

 

Yes.

According to the Chicago Board Options Exchange, typically only about 30% of options expire worthless in each monthly cycle. Only about 10% of options are exercised during each monthly cycle, usually in the final week before expiration. In fact, over 60% of all options are traded out in the marketplace.

These stats are on the CBOE website... somewhere.