Genuine question about why locking in capital gains now is the wrong move.

I understand selling at a time like this is generally considered the wrong move, but if signs are pointing to this being the start of more drops (because China has been the only tariff retaliator so far) then why would I not want to lock in earnings I’ve made over years? Seems like the consensus is to stay in and let the market take away all my earnings while staying in this market that looks bleak. Is a HYSA during times like this not a good safety buffer?