"While the prospective returns are tempting, investors should be aware that it is just as susceptible to supply and demand as other assets, but will not necessarily have the inherent value behind it.
"It is important to remember that these are speculative assets that don’t fit within traditional investment portfolios, as they are neither a traditional commodity, such as gold, nor a traditional currency," he said.
However, younger investors argue that cryptocurrencies are fast becoming mainstream and should be treated with the same amount of respect as stocks.
Jay Smith, a 31-year old cryptocurrency and stock investor in Basingstoke, said investing in the 10 largest cryptocurrencies was no more risky than owning some stocks, which could also be very speculative.
"The real risk in crypto comes from the smaller coins. The biggest ones are well established and serious companies, fund groups and even central banks are now taking them seriously," he said.
However, he said buying niche, "joke" coins like Dogecoin was a recipe for disaster as they did not have the same credibility as Bitcoin.
Milan Barua, 31 in London, has 80pc of his investment portfolio in cryptocurrencies. His most successful investment has been Dogecoin, which has delivered him 600pc returns.
"It is a better investment than stocks because it does not follow classic rules of economics. Prices can be influenced by internet forums or tweets from Elon Musk, which means that you can make better returns than on the stock market," he said.
Mr Barua added that another advantage was that there was no exchange rate risk. "I can buy crypto in pounds whereas I have to pay in dollars for American shares," he said.
Mr Flynn encouraged younger investors to learn as much as possible about different investments – not just cryptocurrenies – before risking their money.