Bitcoin and a slew of newly minted altcoin exchange-traded funds have crashed, erasing all gains made since just before Donald Trump retook the White House and wiping out the speculative premium that had defined the era’s digital-asset boom. Despite the president’s pledge to make America the world’s crypto capital, Bitcoin has plunged 50% from its peak to trade around $63,000. Cryptocurrencies beyond Bitcoin have fared even worse, with a gauge tracking 50 smaller tokens tumbling 67% from a recent peak in October.