Why would they think it is not a safe asset and if so what would they do instead with it? Also: Why do you think this shift would be rapid like in a phase shift?
Reinforcement in raised rates => depression and stock market crash => investors stop using US equities and real estate as value store.
And Feds needs to raise rates - because of negative effective funds rate (https://www.lynalden.com/wp-content/uploads/newsletter-2022-...) - this is also something that people might not perceive for a long time - but then suddenly see it.
Also, again my question: What would people buy instead?
I don't know - most probably it will still be much slower than bitcoin maximalists imagine (see for example https://noahpinion.substack.com/p/inflation-is-up-but-the-in...). Maybe it will be like going bankrupt: “Gradually, then suddenly.”