This is what happened in 2013 with boom to $1000 Bitcoin followed by huge crash to $200 Bitcoin, and in 2017 boom to $20000 Bitcoin followed by huge crash to $3000 Bitcoin.
I really can't see any massive dumping happening in 2021 because compared to 2017, there was a huge scam events that happened in the past that completely reversed the trend of the market. Right now, we have the support of institutional money and more keeps on coming so I really doubt that there's going to be another 2017.