Famed economist Mohamed El-Erian says he bought some bitcoin a few years ago — but misjudged when to sell due to “behavioral mistakes.”

The Allianz chief economic advisor revealed he purchased an unspecified amount of bitcoin in the “crypto winter” of 2018, when the world’s largest digital coin plunged close to $3,000 after a monster rally that took it above $19,000 a year earlier.

“I felt compelled to buy it — I really did,” El-Erian said in an interview with CNBC’s Dan Murphy on Monday. “I felt like I had framed it. I had this level, I had an entry point.”

He subsequently held on to his position until late 2020, when bitcoin regained the $19,000 level. A few months later, bitcoin extended its wild run, hitting a record high above $60,000.

Bitcoin is now trading well above the $60,000 mark, hitting a new all-time high of more than $68,000 last week. It was last trading at about $65,810, up nearly 3% in the last 24 hours, according to Coin Metrics data.

Analysts have pointed to inflation fears and the launch of the first U.S. bitcoin-related exchange-traded fund as key factors driving the rally. Meanwhile, bitcoin’s underlying blockchain underwent a major upgrade over the weekend.

Still, bitcoin and its smaller competitors — which include ethereum and XRP — are notoriously volatile assets. Bitcoin at one point halved in price after initially topping $60,000 as Chinese regulators stepped up a crackdown on crypto mining and trading.

“You really don’t want to ask me about valuations, because I don’t quite understand why $60,000, as opposed to $68,000, is the right level,” El-Erian added.

El-Erian categorizes bitcoin investors into three buckets: “fundamentalists” who are in it for the long haul, professional investors looking to diversify their portfolios and day-trading “speculators.”

The economist said he would only feel comfortable buying again once some of the speculators in the market are “shaken out.” The first two types of investors, he says, are “really strong foundations for that market long-term.”

“These other two levels are pretty solid in terms of supporting bitcoin and other cryptocurrencies,” El-Erian said. “The key thing here is the underlying technology and the model. And those two things are going to be very influential in the period ahead.”

Like bitcoin’s evangelists, El-Erian believes the cryptocurrency is a “very disruptive force.” But he doesn’t think it will ever become a “global currency” rivaling the U.S. dollar.

“I think it will always exist in the ecosystem but it’s not going to be a global currency,” he said. “It’s not going to replace the dollar.”

Unlike crypto skeptics, however, the former PIMCO CEO doesn’t believe bitcoin can be “regulated out of existence.”

As more and more mainstream investors jump into the market, El-Erian thinks the crypto industry should start engaging with regulators sooner rather than later to avoid the regulatory headwinds facing internet giants like Amazon, Google and Facebook.

“When I speak to people in the crypto industry, I say you have a responsibility not to repeat the mistake of Big Tech,” El-Erian said. “The big mistake of Big Tech was they didn’t realize they were becoming systemically important, so they didn’t engage in preemptive regulatory discussions.”

“Crypto needs to take seriously that there are concerns about illicit payments; there’s concerns about fraud; there’s concerns about stability of platform,” he added.

El-Erian warned that China may look to get ahead of the U.S. and other countries in the West on digital currency and blockchain technology.

While the world’s second-largest economy has largely banned cryptocurrency-related activities, it has ambitious plans to issue its own central bank digital currency and to apply the blockchain technology that underpins many cryptocurrencies in other fields, such as intellectual property.

“If the West is not careful, China will define standards for the world,” El-Erian said.