If he is worried and disappointed that his investment in Bitcoin will fall, he should not invest in Bitcoin from the start. He should have understood that investing in Bitcoin is quite risky. This is not the way to invest with high returns in a short period of time. He should know that his investment can drop significantly and he must accept that because he invests in risky assets. He should have held it for a longer period of time, maybe in the next 3 years his investment will bear fruit. The point is to stay patient and HOLD.
Every investment is risky. but I agree, you should always be prepared for the downfall. Yeah, the spirit only comes with experience, but it's not hard just to do a little research and be somewhat prepared.