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.
There are people who never buy if Bitcoin nose dives to $5,000 from its current price $60,000+. They will say buying at that price is catching a falling knife. Didn't we experience it when Bitcoin crashed to $3200 from its ATH in 2017? These ones waited until price picked and they chased it.
From the various options above, I think they one that will greatly kill Bitcoin is the
number 3. Others won't bother the Bitcoin community as much.
A trillion dollar asset going to zero? I don't think people ask that kind of question with similar assets? Will silver ever be worth zero? Will google someday be worth zero? If we talk about 100 years from now maybe because you never know. But if we talk about nearer futures it is practically impossible. It is much more likely that its value will reach $1M and more.
It's simply because people still erroneously think Bitcoin is a bubble. People forget that there is a paradigm shift going on as it were and that Bitcoin is leading that shift.