Would bitcoin be destroyed if a wealthy organization obtained a CPU majority for a sustained period? Inspired by this question ("Could bitcoin be destroyed by an entity cornering the market?") and the top comment on this answer to this question ("How much would it cost to execute a 51% attack?").

The United States government hates currencies competing with its own, so it may at some point have great motivation to destroy bitcoin.

Answers to the first question show that the government couldn't destroy bitcoin by cornering the market. Answers to the second question show that it would be very expensive for an individual to sustain a 51% attack.

However, the top comment on the referenced answer reads:


  A related point is: why bother mounting such an attack? If you were
  indeed successful and started building your own block chain, then
  confidence in Bitcoin would plummet and investors would sell out their
  positions (assuming their positions could be sold out). The price
  would drop through the floor and the value of your exploit would be
  reduced to nothing.


Given the upvotes on this comment, many appear to agree that a sustained 51% would plummet bitcoin values. This would lead to extreme distrust, and possible collapse, of the system.

But $16.35M + $84k / day is likely spare change for some branches of the U.S. government. If the U.S. sustained a 51% attack almost indefinitely, would this destroy bitcoin? For them, the value of their exploit would hardly "be reduced to nothing", instead it could possibly save their inflationary currency.

One might even say the 51% attack investment would pay itself off with the amount of inflationary income they could generate given the downfall of bitcoin.

This same scenario may apply to any wealthy organization. One could bet on bitcoin falling and then apply this attack for profit. The IMF or a different government could have reason to attack Bitcoin.
One of the questions you linked to has the wrong chosen answer— Bitcoin can also be destroyed by a sufficiently deep pocketed attacker which corners sufficient marketshare of coins to enable causing debilitating volatility. Probably won't require any where near majority share to create volatility. I added my claim at that question.

Yes Bitcoin can also be destroyed if an attacker cornered sufficient Proof-of-Work to disrupt the system. Even if developers release new protocols after the attack, there will be chaos as to which fork to trust and reputation will be shattered.

Might not even require 51%, as the minority share attacker could cause many transactions to be randomly delayed, which is also potentially debilitating to a currency.

As the prior answer points out, one the keys to hardening a P2P currency is to make the Proof-of-Work more difficult to corner. But that alone is not sufficient, as the volatility of the value is another attack vector. I am contemplating solutions to harden against both classes of vulnerabilities.

Bitcoin might even be attackable simply by talking and enumerating the flaws in it. We could see a crash at any time if enough people become concerned. So public opinion is another attack vector.