We witnessed the perfect case of FOMO in late 2017 when Bitcoin went on a rampage and hit $20,000 USD. Nobody knew when it was going to stop, it was possible that it could have gone way higher and then the price started to tumble.
I saw many traders angry they bought in at Bitcoin's all time high around $19k thinking it would continue to rise. At the time of writing this, Bitcoin is hovering around $6.5k (quite a drop, eh?).
FOMO trades will lose you money. It's possible you might get lucky and buy into a wave mid-way and get out unscathed, but there is a higher than average possibility that you'll lose money.
this is a lesson most traders and investors will learn the hard way. greed is a very powerful emotion, and it usually takes a couple bad losses before the danger of fomo starts to sink in for new traders.
and like you said, even experienced traders fall victim to fomo sometimes---it takes a lot of resolve to keep your emotions in check all the time in a volatile market like bitcoin. that's why i have a hard rule about having a plan (entry, target, stop loss) before taking a position. no plan = no trade.