Bitcoin, the volatile digital currency that briefly became a trillion-dollar market, plummeted on Wednesday as its month long slide morphed into a frantic selloff.Cryptocurrencies have soared over the past year on a wave of speculative excitement, encouraged by famous backers as varied as Elon Musk, Paul Tudor Jones and Snoop Dogg.That gave the small but growing crowd of bulls a feeling of inevitability that cryptocurrencies would grow into a remarkable asset class in their own right. Bitcoin, they wagered, may even fulfill its initial vision and become a legitimate alternative currency.But the same momentum that drove prices higher is now sending them relentlessly lower.Bitcoin, which traded around $7,000 at the beginning of 2020, climaxed at $64,829 in mid-April. Since then, it has dropped by 41% to $38,390 as of 5 p.m. ET Wednesday and earlier in the day fell as low as $30,202.