I learned about this word today too. It stands for 'Joy Of Missing Out".
You were thinking of buying a coin and later that coin dumps to oblivion. That's JOMO!
Yes so many times. In fact this has happened equal number of times as FOMO so many times I think of buying a coin and see it sinking next day and I get so happy. But generally people will see that happening lesser number of times because we don't follow the trades that we have not taken. We generally only see the charts of the coins that we have brought and then continuously regret about buying or selling it.