Honestly, I can't think of any serious reason for bitcoin to drop to $1 because bitcoin is not like all altcoins. It is completely decentralized, not controlled or managed by anyone, so risks like minting, rugpull...are never possible. Moreover, the demand for bitcoin is also completely different from altcoins, if bitcoin drops to 15k or 10k, people will also buy it massively. So it's impossible for bitcoin to drop below $1k, let alone $1. If this question had been asked 10 years ago, there would have been doubts about bitcoin, but things have been very different so far.
People trust bitcoin so much that if unfortunately it comes to 1$ people will buy more at that time as an opportunity to get benefit. You are right that bitcoin cannot go Down to 1$ but its a cryptocurrency and everything can happens here.
Everyone should be prepared for every situations and I think that if it comes to 1$ then people demand will be higher as people select bitcoin at that time when price is not much higher so increasing demand will increase the Bitcoin's rate.
If people are afraid of such a lower price then it can happen that bitcoin goes more down which can cause bitcoin to disappear which is not possible presently and future is not predictable we have no knowledge about future.
No one knows the future, but with what bitcoin has and is achieving, a bitcoin drop to $1 is extremely unlikely, and that's why I believe it can't drop to $1. But if you still hypothesize that it is possible then I believe it will be a terrible crash if bitcoin drops to $1. But I don't believe many people will buy it when it's only $1, panic is inevitable and people will sell everything and run away. If people have faith in it, as I said when bitcoin dropped to 10k, people bought it massively, how can it fall to $1? If you don't have the confidence to buy bitcoin at $1k or $10k, you won't have the guts to buy it at $1.