...but the idea that we should have a moral responsibility to upheld Bitcoin because "otherwise people would not know whom to trust and the whole industry would collapse" is equivalent to the cry from the ludicruously overbloated monopolized taxi racket against Uber and liberalization in general.
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I never said anything about a "moral responsibility" to uphold bitcoin, nor what you put inside quotation marks. Please do not misrepresent what I actually said.
My point is that I think the state of the ecosystem, and the crypto-value-store proposition itself, is so new/unstable/untested, that bitcoin being unseated in the near/medium term stands a good chance of causing a crypto depression. A possibility that you seem to ignore. I respect Smooth's response to ack the theory but disagree on the probabilities. I think you too should consider the probabilities, or at least articulate your analysis of them better if you are indeed taking that line of thought.
This is coming from several years worth of discussions with various people, many of whom are sophisticated investors, execs at successful companies, etc, etc. Many have been tip-toeing in to Bitcoin one way or another, and I think a flip right now in where the value store is in the ecosystem would cause many of them to basically say: "eh, too chaotic right now. I'll wait a while until taking another look." That's problematic for me, in that I think the ecosystem as a whole needs to contain far more value in terms of fiat-market-cap in order to even begin to scratch the surface of the real benefits of the technology for the world. Thus, I consider Bitcoin remaining #1 for the foreseeable future, in order to thus yield the highest chance of more cryptocapitalization in general, as optimal right now.
That said, I concur with others that there will be an ecosystem of coins, with maybe 3-5 being fairly strong. Most likely outcome in terms of relative market-cap seems like a power-law distribution to me, though, since it's a free market in a domain that exhibits strong network effects.
My biggest quibble with the posited result of Bitcoin being overtaken is exactly your last paragraph. 3-5 fairly strong coins doesn't upend the entire premise of scarcity at all. It simply gives us a scarce ecosystem of 3-5 fairly strong coins. Of course, if that turned into 100 equally strong coins or something like that, with more fairly strong coins arriving every day (both highly improbable), then scarcity would indeed be completely destroyed.
But in practice most of the concern over destroying scarcity is based on a false premise. People indeed observed 100s of alts and more being created every day but, importantly and incorrectly, ignored the question of whether they are actually fairly strong or fairly worthless.
The most important conclusion, though, is that even if the theory and conclusion (that Bitcoin being overturned would be catastrophic) is correct, that alone won't prevent it from happening. It simply means that cryptocurrency either doesn't work at all, or will, as you suggested, take 10+ more years to really work. There is no alternative short of a central authority imposing an outcome by its will, which makes the whole experiment an abject failure anyway.