Bill Gates, the philanthropist and former chief executive of Microsoft, is concerned by the crytocurrency craze, saying that the anonymity offered by the new technology has “caused deaths in a fairly direct way”.

Speaking during a Reddit AMA, Gates argued that “the government’s ability to find money laundering and tax evasion and terrorist funding is a good thing.

“Right now cryptocurrencies are used for buying fentanyl and other drugs so it is a rare technology that has caused deaths in a fairly direct way.” In contrast to cash, which is also untraceable, cryptocurrencies can be used remotely, which removes another avenue of control, he added.

Gates also suggested that investing in the sector is a bad idea: “I think the speculative wave around ICOs and cryptocurrencies is super risky”.

Bitcoin and cryptocurrencies – what digital money really means for our future Read more

In the group interview, Gates had harsh words for some other speculative technologies. Elon Musk’s Hyperloop concept, for instance, which involves using a railgun to fire a passenger compartment down a low-pressure tube at speeds of several hundred miles per hour, was dismissed: “I am not sure the Hyperloop concept makes sense,” he said. “Making it safe is hard.”

But Gates was positive about the overall direction of technology, dismissing concerns that rising automation could have negative consequences for the wider economy, and citing natural language understanding as the technology he’s most looking forward to over the next decade.

“Automation has been driving productivity ever since the industrial revolution including things like tractors and garment making,” Gates said. “With software this will continue to accelerate so we need to think about how we educate people for the new jobs that will emerge.

“Overall automation is a great thing – eventually we won’t have to work as much but we are still at least a generation away from a big change there.”

Gates is not the only former tech executive to have a negative view of cryptocurrencies. Steve Wozniak, the co-founder of Apple, revealed on Tuesday that he had lost seven bitcoins to a scammer.

“Somebody bought them from me online through a credit card, and they cancelled the credit card payment,” he told a conference in India. “It was that easy. And it was from a stolen credit card number, so you can never get it back.” At the time the scam was carried out, the bitcoins were worth just under $5,000; now, their value tops $70,000.

Gates had one final word of warning for readers of his interview. Asked by one user: “Is it true that if I forward the email in my inbox to 100 people you will give me money?”, he replied, simply: “No.”