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!
Happened with once or twice back few years when there was project who was in hype and the coins were in demand so as profit motive I also wanted to invest in it but didn't have the money at the time so was feeling bad but later on the project team abandoned it due to which the coin lost it's major stake and investors looses all their funds.So have also came across new word now JOMO.
You're lucky not to invest in the project because you don't have the money. If you have money and invest in the project but the project turns into a scam or the team leaves the project, you will be very disappointed because you have chosen the wrong project.
Most of us have experienced but are not aware of the term. We invest in up-and-coming projects in the hope that we too can benefit. After the token or coin price does go up, we don't immediately sell it but keep it on hold. And we are too late to sell it while the price plunged to the bottom.