imagine all those people who sold Apple, Microsoft, Amazon in the 1999 bubble. I bet they own those stocks again, probably cashed out and bought a lambo, only to buy back the shares at double to even 10x the price. will the same happen to bitcoin?
People that sold at end of 2017 for sure bought back already. in 2018 and 2019. I doubt anyone waited until 2020. They did not sold their cars but just bought back with fiat they got in 2017. Ofcourse none of them sold at $20k. Some sold at $10, some even before. It is impossible to sell at top. The same impossibility as buy on bottom.