Many advisory services that only sell options will tout this statistic. While it may actually be true, it may be for reasons not so readily apparent. Here's how I see it;

  • Option buyers range from the absolute beginner to the seasoned professional
  • Option sellers typically have a little more experience
  • Experienced traders, on average, are more successful than those less experienced

So if most beginning option traders are buying, and a larger percentage of experienced traders are selling, the odds may just favor the sellers... but I wouldn't go so far as to say that all the sellers win and all the buyers lose.

As far as mechanics, selling is basically the same as buying; you enter an order to open the trade, and you enter an order to close the trade... the difference is you Sell To Open (vs Buy To Open), and you Buy To Close (vs Sell To Close).

Zardoz, Florida, and Pete already gave some great detail, but there are still plenty of others to consider, such as Risk Profile, Rights vs Obligations, etc. As with all trading and investing, the participant must be fully aware of all potential outcomes if there is to be any expectation of success.