The bigger they are, the harder they fall; is a saying for a reason. There is no such thing as “too big to fail” otherwise the East India Trading Company would still be in operation.
Sometimes. IBM was still considered big when Buffet invested in them early in the 2010s. And it took almost a decade worth of bad performance for him to finally exit. It might be slowly sliding into irrevelance but its stock hasn't completely tanked -- during or after that period.