What set of conditions (technical or socio-economic) can crash blockchain or bitcoin to zero USD? Is this notion of bitcoin crashing inconceivable at this point 10 years into its existence (so long as there is electricity and the internet)? My corollary question is: Can bitcoin be obsoleted by another cryptocurrency? What would that path of obsoletion look like for bitcoin? For example, I hear about other crypto currencies like Etherium or Lightcoin or Bitcash or Altcoin or Bitgold. What would be signs to look for that would make it prudent to cash out of Bitcoin to buy Etherium, for example.
I can appreciate your line of questioning. I think many, most or all of us have had to ask theses questions in our early discovery of
BTC. Rightfully so, Bitcoin is not like any currency or tech we've ever experienced and anyone investing will want to know that their investment is on reasonably solid ground.
Learning why Bitcoin is immutable & censorship resistant is the key to answering your question
for yourself. Sure, everyone can give their conclusions on how it could happen, war etc. Because Bitcoin is a relatively new concept and a new proposal to value, scarcity and money in general, it requires each of us who questions it to rethink, re-learn and discover the hard fundamental values of this new digital money. It's not exactly something most people simply 'get' in their first attempts but with perseverance and decent teachers it's easier to jump into the Bitcoin rabbit hole.
Nobody wants to miss this train but because so few are willing to understand money and value, most will miss it no less. Redefining money will take time, we are still so early.
May I suggest starting with Andreas Antonopoulos if you're not already familiar.
https://www.youtube.com/channel/UCJWCJCWOxBYSi5DhCieLOLQ