If you've been even slightly tempted to invest in digital currencies such as bitcoin, Ripple, or Etherium, you might want to listen to Warren Buffett. In a recent interview on CNBC, the investing guru said he feels almost certain that putting money in this market "will come to a bad ending."

By now, everyone has heard about the mania over cryptocurrencies—a form of encrypted digital money that average investors can  trade just like stocks. The frenzy was sparked by bitcoin, the oldest and most well-known cryptocurrency, which soared more than 1,900 percent in 2017 to around $20,000, before falling to around $14,000 this month.

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There are now hundreds of other such currencies that can be traded—and new ones are regularly being created. Eastman Kodak, for example, just announced Kodakcoin, a cryptocurrency for photographers to use to manage rights and fees for their work. The company's shares rose 245 percent on the news.

But don't be fooled.

“People are desperate for anything that can bring them instant wealth, but [cryptocurrencies] are very risky investments because the technology is new and unproven,” says Jerry Brito, executive director of CoinCenter, a D.C.-based nonprofit research and advocacy group focused on the public policy issues facing the cryptocurrency. “You shouldn’t invest in stuff you don’t understand, and you shouldn’t be investing money that you can’t afford to lose,” he says.

If that isn't enough to deter you, we've got four other reasons. Read on.

Fraud and Security Issues

The most popular way to buy and sell cryptocurrencies is through an exchange, where buyers and sellers come together online to trade.

But regulators, including the Consumer Finance Protection Bureau and the Securities and Exchange Commission, which since July has become much more active in cryptocurrency oversight, have been warning that some exchanges are fake. Unsuspecting investors can easily open an account at a fraudulent exchange and submit money to buy, say, bitcoin. But the criminals steal the money and the investor never receives the bitcoin. 

Even legitimate exchanges may not have adequate security in place. Last month, a prominent South Korean exchange was forced to shut down after being raided by hackers who stole the cryptocurrencies. In such cases there is very little authorities can do to recover the funds.

Matt Mitchell, a tech security researcher, says that while lax security is a big risk, there are some exchanges that have invested in technology to lock down their systems. Among them, he says, are Coindesk, GDax, and Kraken.

Initial Offerings Provide Few Protections

For some investors, one attraction of cryptocurrencies is the ability to participate in an initial coin offering, or ICO. Investors jump in, hoping to get the digital currency at a low price and then profit as it rises.

But ICOs are far riskier than stock IPOs—and have other key differences.

For one thing, in an IPO, the average investor can't easily participate, says Christina Tetreault, staff attorney for Consumers Union, the policy and mobilization division of Consumer Reports. Companies going public award their shares to institutional investors, which may then make them available to their customers as long as their income meets certain thresholds. In this way, average investors can't take undue risks that could wipe them out. 

That's not so with ICOs—anyone can participate. The result is that some overeager investors may take on too much financial risk, says Tetreault. 

Another difference: ICOs don't have to live up to the same high standards as IPOs. Before a company can file to go public it has to show a minimum earnings level, undergo audits, issue a prospectus that explains the company's financials, etc. In other words, by the time shares are offered to the public there has been some due diligence, the shares are considered viable, and investors have access to information.

No such safeguards exist for ICOs. Cryptocurrency issuers may not even have a track record investors can examine to see if the company is financially sound. While many do publish a white paper explaining why they are raising funds, there is no legal requirement that they do so.

In December, SEC chairman John Clayton warned investors that the regulator may not be able to effectively pursue bad actors or recover funds for investors, partly because these markets often operate outside of the United States.

There Will Be Fees

It's true that when bitcoin was created, the idea was partly to create a bank alternative as a way to avoid high fees, says Mitchell. But trading cryptocurrencies will still cost you, usually a fraction of a percent of the total transaction amount, depending on the exchange.

You can avoid exchanges and buy and sell bitcoin, for example, through a cryptocurrency wallet—an app you load onto your smartphone. The fee you are charged depends on the total number of people globally who are buying and selling that currency. The more people trading, the higher the fee, Brito says.

A year ago, before most people were thinking about trading bitcoin, a wallet transaction fee averaged around 6 cents, according to Bitinfocharts, a fee tracker. That fee rose to around $55 per transaction, when the number of transactions reached their height in late December. 

Cryptocurrencies are Easy to Lose

When you buy a cryptocurrency and place it in your smartphone's cryptocurrency wallet, it might be safer than taking the alternative route, which is to store it in a wallet located at an exchange. That's because exchanges are more likely to be hacked than your smartphone. To date, billions of dollars worth of bitcoin and other cryptocurrencies have been lost on exchanges to hackers.

But even using a smartphone wallet, you could still lose your bitcoin. If you do not back up the app and lose your phone, you're out of luck. If you misplace or accidentally delete your "key"—a long password that's generated when you open your account—there is no "forgot my password" option to help you.

Mitchell says that phone operating systems could also become corrupted, which might delete a wallet from a user's phone. That's why there is new hardware now available for people to back up and secure their wallets.