The first time I heard about Bitcoin was on the news, but the reporter only briefly mentioned the appearance of a new currency called Bitcoin and did not provide any further analysis. It was in 2009, and I was also just aware of its existence but did not pay much attention to it.  Until 2017, when I tried to buy a piece, and the price was about 4,300 US dollars. After about 3.4 months, the price rise to 20,000 US dollars, so I sold it because I thought there would not be another opportunity to see a day with a price over 20,000 US dollars. This was probably my biggest regret.