It&#x27;s not necessarily &#x27;irrational&#x27;. A 51% miner could profit from Bitcoin&#x27;s downfall, or by threatening others, or even by bluffing an attack. See, e.g., the Goldfinger Attack in <a href="https:&#x2F;&#x2F;www.cs.princeton.edu&#x2F;~kroll&#x2F;papers&#x2F;weis13_bitcoin.pdf" rel="nofollow">https:&#x2F;&#x2F;www.cs.princeton.edu&#x2F;~kroll&#x2F;papers&#x2F;weis13_bitcoin.pd...</a>.