These hedge fund billionaires bought shares of a spot Bitcoin ETF in the second quarter; some experts anticipate substantial upside in Bitcoin in the next decade and beyond.During the second quarter, several billionaire-led hedge funds bought positions in the iShares Bitcoin Trust (IBIT -1.57%), an exchange-traded fund (ETF) that tracks the spot price of Bitcoin (BTC -0.01%). The fund is issued by BlackRock, the largest asset manager in the world.Israel Englander of Millennium Management added 3.8 million s ...