Too much greediness will certainly ruin us and this is what happens to your friend.
I have this bad experience as well in the previous Bullrun. I thought everything will be fine, I thought the market will continue to move high, If you see on the speculations board that time, everyone is very positive and optimistic but suddenly, dumps come and give me the nightmare.
And from that, I learned a lot, and that we don't be positive always but also, we need to analyze the market if we have to sell or just hold.
Me too, it did really give me out some lesson in life and having those common line to be followed "Buy when everyone is on fear and sell when everyone is greedy"
This is the thing ive been following now when it comes to market trend.I have committed the same mistake as yours on that first bull run we do have where
everything is hyping and growing without realizing that I should have secured out my profits while its still at peak but due to greed you would really be
ending up on holding up and ask for more until you realized that its too late since the market had already flipped out.