In order to evaluate the risks of bitcoin, I would like to know what possible events could cause bitcoin to go to $0. I want to know things that would be truly devastating to bitcoin, or possibly all cryptos. I am not saying anything like this is likely, but for me it is important to understand the potential risks associated with it. I also want to know what events might cause a price decline that bitcoin would never be able to recover from.
For instance, I have heard that if SHA256 (or maybe some other type of security) is cracked, then bitcoin will essentially become worthless. Also, another example of a doomsday scenario for bitcoin would be the emergence of a competing crypto that is superior in every way, causing btc price decline slowly to very little, as market share moves to the other currency. On the other hand, something like a U.S. ban on bitcoin, as unlikely as it is, would not cause the price to go to 0, it would just find a much lower equilibrium price very quickly, and then probably slowly rise from there.
As I own bitcoin, I am concerned that one day, I could wake up and bitcoin will have gone to 0 while I was sleeping due to some unforeseen risk.
$0 is utterly unrealistic and almost certainly would never happen, even if SHA256 was smashed and there was an apocalypse there would be some nutcase collector who wants to catch them all, he'll pay you some cents for the almost worthless Bitcoin.
However, Bitcoin falling under $10 would be devastating and would signal the end of Bitcoin for sure, for there must have been a good reason to drop that low and effectively wiping out the hundreds of millions of USD invested into the Bitcoin ecosystem.
There is only one real scenario where Bitcoin dropping below $10 and close to $0 being a semi-good thing, that is if a large holder were to unload onto the market (think:Satoshi) there are several people who could bring the price under $10, however this effect would be limited and the price would certainly recover if it became obvious to the world that a single manipulator was causing the mayhem. (If the world thinks it's the market at large and not the actions of a single person, then people might panic and mass sell offs could destroy the confidence in Bitcoin)
It's a semi good thing because if the price recovers, then it was effectively a redistribution of wealth to the Bitcoin community, however if the market at large panic sold and everyone got out, then the price may not recover, and that would be bad.
Possible situations where Bitcoin drops to $0-$10 and never returns mostly would deal with competition.
The competition so far has been weak (think:Litecoin) but is growing stronger every day (think:Monero, Ethereum) and it's possible that some form of competition becomes attractive enough to start drawing money out of Bitcoin.
However, I don't see Bitcoin being fussed by this competition anytime soon, at the moment the competition fights among itself.
At the end of the day, diversifying a little is the best bet. My current recommendation is to keep 1% to a maximum of 5% of your CryptoCoin wealth in some of the alts that actually have utility and 99% to 95% in Bitcoin, as no serious competitor really exists yet.