When majority investors in fear, wouldn't they sell off their assets first before buying the dips?
Ehh, it really depends on the investor honestly. Some will be fearful and some, the more experienced ones, will most probably be buying the dips. And buying dips doesn't necessarily include dumping their assets before buying dips.
Isn't it possible for them to take other investment options when they feel the fear will last long? hence bitcoin could be one of the option for them.
Very unlikely in my opinion. Bitcoin is still a scam in the eyes of a lot of people(especially people aged 40+).