The last time Bitcoin was priced under $200 was in January of 2015. You're correct that it hasn't experienced a drop of 50% at any point since then.

On the other hand, Bitcoin was also priced under $200 just over a year earlier, in November 2013. In December 2013 it spiked over $1000 before crashing. The $200 in January 2015 is where it eventually stabilized.

This doesn't invalidate your comment, by any means, but it does illustrate that such a collapse is not out of the realm of possibility.

(All prices sourced from https://www.coindesk.com/price/)