It was the investment that was definitely going to make you a millionaire overnight. The type of asset that would carry you with it on the unstoppable tech wave barrelling into a dazzlingly bright future.At some point in the last five years, we believed that one in every eight UK adults has bought at least one cryptocurrency – digital or virtual-only assets that are held, traded and transferred electronically while being kept secure by cryptography (hence the name). Transactions are managed not by a central bank but on a peer-to-peer basis through technology that shares and synchronises data across multiple sites.Thousands of cryptocurrencies have failed but there are several thousand more out there and, like so many other aspects of our financial affairs, a handful – including Bitcoin, Ethereum, Tether, Binance Coin and Cardano – currently control the vast majority by market cap.They’re the ones we’ve at least heard of, even if that’s as far as we get, even though vanguard Bitcoin has been around for more than a decade. And worryingly often, that is indeed as far as we get.Data from behavioural finance specialists Oxford Risk suggests 36 per cent of UK retail cryptocurrency investors admit their understanding of the sector was either non-existent or poor when they bought.Even after owning cryptocurrencies, almost a quarter of investors still rate their knowledge of the assets and investment opportunities in the sector in the same vein.Oxford Risk’s study found around one in eight adults say they have bought cryptocurrencies in the past five years and just 21 per cent of them say their knowledge of the sector was good when they first invested.The figure only rises to 33 per cent after investors begin building up more knowledge after buying in.Greg B Davies, head of behavioural finance at Oxford Risk, said: “The concern is that too many people are buying blind without knowing what they’re doing and are being influenced to invest by rising prices and other people encouraging them to have a go.“That is worrying if people have substantial amounts invested in cryptos and do not understand what they have bought.”With demand being driven by emotional factors, not least the fear of missing out, investors report buying in off the back of encouragement from friends and families and reports of huge price rises.All of this becomes slightly alarming when you clock the nausea-inducing volatility investors face when strapped into one or more of this kind of asset. And the ride is getting rougher all the time.After closing in on $65,000 per bitcoin in April this year, a few choice words from Tesla boss Elon Musk and concerns over a Chinese crackdown on cryptocurrencies saw values crash $30,000 by the end of May.At the same time, Ethereum, the second-largest cryptocurrency, also fell by 50 per cent from US$4,000 per ether token to under US$2,000 today.In June, its use in a ransomware attack sent Bitcoin tumbling further and amid a massive global regulatory clampdown on cryptocurrencies, the Chinese government has upped the ante on its anti-cryptocurrency stance over fears around social destabilisation and competition for the central bank’s digital yuan, by banning the “mining” or production of new digital coins or tokens.This weekend, as analysts began using the word “danger” in their assessments of Bitcoin and Ethereum, reports starting coming in that Chinese cryptocurrency miners have started dumping the hardware they use on the secondhand market.This is in the nation that research by the University of Cambridge found was responsible for 65 per cent of all Bitcoin production last year.And yet despite it all, we somehow remain enchanted.