Bitcoin rallied, lifting crypto-tied stocks like Coinbase, Robinhood, and Strategy. The crypto pop comes after a post from Trump amid the war in Iran.

For years, the largest Bitcoin miners operated on an article of faith as much as a business model: that the coins they minted were worth holding, that scarcity would reward patience, and that the balance sheet accumulation of digital currency was itself a kind of competitive moat. Some of them built stashes worth hundreds of...