Is the definition of a "bubble" invalidated if the stock goes back up some time after the crash? It did drop initially from $20K to a low of $3,200, which is 84%.
Yes it is. If you had invested in the stock market at the height of the “””bubble””” in 2000 you would be off well now. In hindsight it was not a bubble. You may disagree but sadly you probably didn’t have that perspective at the time.