As virtual currencies plumbed new depths on Wednesday, the MVIS CryptoCompare Digital Assets 10 Index extended its collapse from a January high to 80 percent. The tumble has now surpassed the Nasdaq Composite Index's 78 percent peak-to-trough decline after the dot-com bubble burst in 2000.

Like their predecessors during the Internet-stock boom almost two decades ago, cryptocurrency investors who bet big on a seemingly revolutionary technology are suffering a painful reality check, particularly those in many secondary tokens, so-called alt-coins.

"It just shows what a massive, speculative bubble the whole crypto thing was -- as many of us at the time warned," said Neil Wilson, chief market analyst in London for Markets.com, a foreign-exchange trading platform. "It's a very likely a winner takes all market -- Bitcoin currently most likely."