Here are some scenerios that can cause the price of btc to fall drastically. (In my opinion, it is highly unlikely and the possibility very slim).
(1) No way to trade bitcoin or exchange it for goods and services.
(2) All governments of the world placing a ban on bitcoin and bitcoin related activities making it highly illegal.
(3) The entire bitcoin network and nodes going offline making it impossible to even make underground transactions in bitcoin.
(4) Another crypto overtaking bitcoin and value and more people shifting investment to this new crypto.
All these things you have said here cannot make the price of bitcoin to drop to a zero, if there is anything that can cause bitcoin to drop to zero then it should be one thing , and that’s when everyone stops making use of bitcoin and also the devs decides to abandon and exchanges stop trading it, that’s the only thing I know that can possibly lead to bitcoin price or value dropping to a zero, but I don’t think such a thing is going to happen, I can’t even imagine it.
The only thing you’re going to be seeing is just this price fluctuation that will be happening all the time. And it is possible that some of the big investors/institutions will sell their assets at some point and cause the market to crash heavily, but still it won’t fall to zero and it stop people from using it.