Simply because the WHALES take the profits whenever there's a 5 to 10 percent growth. The bottom line is Swing trading and Day trading is real and the HODL method is just what it is...
That's the downside of bitcoin wherein whales can manipulate the price of bitcoin to the price they want. The way things are running now, in my opinion bitcoin will be having a hard time reaching $20k this year but definitely it will reach that value but we don't know when.