imagine that today the price of bitcoin was $3, his advice would have led his friend to have losses. with that I mean the following: nobody knows when the price is high and when the price is low, people only make assumptions ... you got it right because the price has gone up, but you could also have been wrong if the price dropped. This is the same as the people who bought when the price was $ 15000 if the price had increased to $ 50,000. so everyone who bought the $15000 would have made a good investment, but as the price dropped a lot and this at  $5000... people call stupid everyone who bought when the price was $15000. But who can say when low is low is when high is high?