South Korea is one of the world’s biggest markets for bitcoin—so it’s no wonder that more than three out of 10 salaried workers in the country have invested in cryptocurrencies, according to a recent study (link in Korean) conducted by job portal Saramin.

Of those who invested in cryptocurrencies, more than 80% made money from it, and about 20% made an average return of 425% on their investment, according to the survey. The average Korean investor owned some 5.66 million won ($5,260) in virtual currencies.

This poll surveyed 941 people via email from Dec. 19 to 20, with about 80% of respondents in their 20s and 30s.

South Korea is the world’s third-largest market in bitcoin trading after Japan and the US, with some 2 million digital-currency investors by one estimate—equivalent to about one in every 25 citizens. The country is also home to one of the world’s biggest cryptocurrency trading exchanges, Bithumb.

In comparison, about 11% of Americans polled by student loan comparison website LendEdu in September said they either currently own or have owned virtual currencies in the past, while 17.2% said they would invest in bitcoin in the future.

In Korea, the term “bitcoin zombie” is used to refer to people who check the cryptocurrency’s price around the clock. The country’s prime minister Lee Nak-yeon even expressed concerns over Korea’s bitcoin craze, warning that it could result in “serious distortion or social pathological phenomena” and that it could lead young people into illegal activities like drug dealing.

Amid the mounting concerns over cryptocurrencies, South Korea’s government proposed new measures earlier this month to curb speculative investments in virtual currencies, such as levying taxes on cryptocurrency transactions and banning underage investors and foreigners from opening trading accounts on cryptocurrency exchanges. Today (Dec. 28), South Korean regulators announced further restrictions on cryptocurrency trading including the banning of anonymous accounts.

A group of activists against government regulation of cryptocurrencies have planned a protest (link in Korean) this weekend in Seoul against what it calls the “tyranny” of president Moon Jae-in’s government.

A group of investors have also submitted a petition (link in Korean) online to the presidential Blue House against cryptocurrency regulation, with over 17,000 signatures collected since the beginning of December—the government must respond once a petition garners 200,000 signatures.

Correction: An earlier version of this story incorrectly stated the launch date of the online petition as today (Dec. 28).