That moment when you buy 1BTC at $2500, and then 3 days later someone buys it at $2000. But I'm guessing that it's the risk involved in investing, so what do I do now? Sell? Or hold on them?
Unrealized loss of 20% is common with almost all the investment asset and it is not peculiar to Bitcoin. If it happens to me, then I will be patient and wait for at least 6 months before taking a decision on whether to sell the coins or not.