South Koreans in their 50s were the most aggressive investors in digital currencies last year, a survey showed, with experts calling for a more cautious approach to the volatile investment destination.

According to the survey by the Korea Financial Investors Protection Foundation, of 2,530 people aged from 25 to 64, 7.4 percent were investing in digital currencies as of end-2018, up 1 percentage point from a year earlier.

The average investment came to 6.93 million won ($6,100), soaring 64.2 percent from a year earlier when the figure came to 4.22 million won.

Investors in their 50s on average invested 12.17 million won, followed by those in their 40s and 30s with 8.06 million won and 5.9 million won, respectively. Those in their 20s also invested 3.99 million won on average, the survey showed.