A major challenge for shorting bitcoin-related stocks is not being able to borrow shares, Left said. Short-sellers typically borrow shares and sell them in the expectation they can buy back the shares at a cheaper price in the future.
Left previously announced he was short the Bitcoin Investment Trust (GBTC), which is traded over the counter, rather than in a formal venue such as the New York Stock Exchange.
"I think if other people were able to get borrows [on GBTC] it'd be down 1,000 percent tomorrow," Left said Tuesday.
However, some respected investors have pointed to the investment vehicle as a way to bet on bitcoin.
GBTC is up more than 2,300 percent this year and is the largest holding of the top-performing ARK Innovation Exchange-Traded Fund (ARKK) at nearly 10.5 percent as of Monday. Fundstrat's Tom Lee said in late October that the Bitcoin Investment Trust was an "attractive" buy.
Left also said he "couldn't get a borrow" to short Longfin, one of the latest stocks to soar on the hype around bitcoin and blockchain.
Longfin closed nearly 5.7 percent lower Tuesday after briefly soaring more than 2,500 percent between Friday and Monday after announcing it was buying blockchain company Ziddu.com. The company's CEO and Chairman Venkat Meenavalli said Monday on CNBC's "Fast Money" that "this market cap is not justified."
An increasing number of mostly tiny stocks have surged following news, or speculation, of the companies' involvement in cryptocurrencies or the blockchain technology behind them.
The U.S. Securities and Exchange Commission has become more active in cracking down on cryptocurrency-related speculation. The commission on Tuesday temporarily suspended trading in shares of The Crypto Company, partly on concerns of potential stock manipulation.
In a sign that the speculative mania is getting out of hand, one very small stock, Future FinTech, briefly leaped more than 200 percent Tuesday despite no clear ties to anything crypto-related.
Bitcoin itself briefly tumbled $1,000 in less than an hour Tuesday afternoon. But the digital currency has proved enormously resilient this year. It shook off several declines of more than 20 percent to rise 2,000 percent over the last 12 months to above $19,000, according to Coinbase data.