Your comment leaves out some key details that need mentioned as not to confuse anyone. I'd like to clarify that this is true for a future alone (if cash settled), but not a futures option.
Selling one futures option and having it expire ITM simply gives the trader a one contract long position in the underlying future contract. OTM is full collection of the premium sold as usual. I've done both many times over the years. One legit strategy is selling a futures option with the intent to be long the contract, just like someone would do with selling an equity put option with intent to own 100 shares.
You can most definitely do this as a retail trader and do extremely well in many cases, but it's also very easy to go to $0 and is not for the light hearted.
Selling one futures option and having it expire ITM simply gives the trader a one contract long position in the underlying future contract. OTM is full collection of the premium sold as usual. I've done both many times over the years. One legit strategy is selling a futures option with the intent to be long the contract, just like someone would do with selling an equity put option with intent to own 100 shares.
You can most definitely do this as a retail trader and do extremely well in many cases, but it's also very easy to go to $0 and is not for the light hearted.