There were several bubbles before that, some of which fell by a much more significant percentage than the price did after 2013. They were involving smaller amounts of money, but huge bubbles can collapse in a similarly spectacular fashion.
It's not the size of the bubbles or the falls, it's the duration of the hangover. I cannot see any circumstances where it takes over three years to regain an all time high. That'll take it beyond the next halving all the while legislation is being clarified, antis are coming around to the idea, all the fork shit will be stone dead by then and media coverage is totally changing in its tone.