This is a contributed post by Bill Harris, former CEO of Intuit and founding CEO of PayPal and Personal Capital.

I’m tired of saying, “Be careful, it’s speculative.” Then, “Be careful, it’s gambling.” Then, “Be careful, it’s a bubble.” Okay, I’ll say it: Bitcoin is a scam.

In my opinion, it’s a colossal pump-and-dump scheme, the likes of which the world has never seen. In a pump-and-dump game, promoters “pump” up the price of a security creating a speculative frenzy, then “dump” some of their holdings at artificially high prices. And some cryptocurrencies are pure frauds. Ernst & Young estimates that 10 percent of the money raised for initial coin offerings has been stolen.

The losers are ill-informed buyers caught up in the spiral of greed. The result is a massive transfer of wealth from ordinary families to internet promoters. And “massive” is a massive understatement — 1,500 different cryptocurrencies now register over $300 billion of “value.”

It helps to understand that a bitcoin has no value at all.

Promoters claim cryptocurrency is valuable as (1) a means of payment, (2) a store of value and/or (3) a thing in itself. None of these claims are true.

1. Means of Payment. Bitcoins are accepted almost nowhere, and some cryptocurrencies nowhere at all. Even where accepted, a currency whose value can swing 10 percent or more in a single day is useless as a means of payment. 

2. Store of Value. Extreme price volatility also makes bitcoin undesirable as a store of value. And the storehouses — the cryptocurrency trading exchanges — are far less reliable and trustworthy than ordinary banks and brokers.

3. Thing in Itself. A bitcoin has no intrinsic value. It only has value if people think other people will buy it for a higher price — the Greater Fool theory.

Some cryptocurrencies, like Sweatcoin, which is redeemable for workout gear, are the equivalent of online coupons or frequent flier points — a purpose better served by simple promo codes than complex encryption.

Indeed, for the vast majority of uses, bitcoin has no role. Dollars, pounds, euros, yen and renminbi are better means of payment, stores of value and things in themselves.

Cryptocurrency is best-suited for one use: Criminal activity. Because transactions can be anonymous — law enforcement cannot easily trace who buys and sells — its use is dominated by illegal endeavors. 

Most heavy users of bitcoin are criminals, such as Silk Road and WannaCry ransomware. Too many bitcoin exchanges have experienced spectacular heists, such as NiceHash and Coincheck, or outright fraud, such as Mt. Gox and Bitfunder. Way too many Initial Coin Offerings are scams — 418 of the 902 ICOs in 2017 have already failed.

Hackers are getting into the act. It’s estimated that 90 percent of all remote hacking is now focused on bitcoin theft by commandeering other people’s computers to mine coins.

Even ordinary buyers are flouting the law. Tax law requires that every sale of cryptocurrency be recorded as a capital gain or loss and, of course, most bitcoin sellers fail to do so. The IRS recently ordered one major exchange to produce records of every significant transaction.

And yet, a prominent Silicon Valley promoter of bitcoin proclaims that “Bitcoin is going to transform society … Bitcoin’s been very resilient. It stayed alive during a very difficult time when there was the Silk Road mess, when Mt. Gox stole all that Bitcoin …” He argues the criminal activity shows that bitcoin is strong. I’d say it shows that bitcoin is used for criminal activity.

Bitcoin transactions are sometimes promoted as instant and nearly free, but they’re often relatively slow and expensive. It takes about an hour for a bitcoin transaction to be confirmed, and the bitcoin system is limited to five transactions per second. MasterCard can process 38,000 per second. Transferring $100 from one person to another costs about $6 using a cryptocurrency exchange, and well less than $1 using an electronic check. 

Bitcoin is absurdly wasteful of natural resources. Because it is so compute-intensive, it takes as much electricity to create a single bitcoin — a process called “mining” — as it does to power an average American household for two years. If bitcoin were used for a large portion of the world’s commerce (which won’t happen), it would consume a very large portion of the world’s electricity, diverting scarce power from useful purposes.

In what rational universe could someone simply issue electronic scrip — or just announce that they intend to — and create, out of the blue, billions of dollars of value? It makes no sense.

All of this would be a comic sideshow if innocent people weren’t at risk. But ordinary people are investing some of their life savings in cryptocurrency. One stock brokerage is encouraging its customers to purchase bitcoin for their retirement accounts!

It’s the job of the SEC and other regulators to protect ordinary investors from misleading and fraudulent schemes. It’s time we gave them the legislative authority to do their job.

William H. Harris Jr.  is the founder of Personal Capital Corporation, a digital wealth management firm that provides personal financial software and investment services, where he currently sits on the board of directors. Harris has founded several companies, including XTec, a cybersecurity company, and PassMark Security, a consumer authentication company. He has previously served as a director for several public and private companies, including MyVest, RSA Security, Yodlee, GoDaddy, EarthLink, Macromedia, Visual Sciences, NexTag, Answers.com, Avalara, Business.com, LowerMyBills, and SuccessFactors. Earlier in his career, he served in various senior positions with Intuit Inc., a developer of financial and tax preparation software, most recently as CEO. He also served as CEO of PayPal Inc., an online payments business. Reach him @BillHarris_PC.

This article originally appeared on Recode.net.