Why are investment ads promising 'guaranteed principal with high returns' dangerous?

The Financial Supervisory Service has warned about illegal fundraising that promises guaranteed principal and high returns while circulating fake videos of investment success stories and the like, and urges people to remember: 'High returns?

Guaranteed principal? There is no such investment.' Recently, cases have been reported of operators taking investment money on the pretext of investing in new technology development, automated trading programs or financial consulting, then stalling on withdrawals and disappearing. Before dealing with any such offer, be sure to check whether it comes from a regulated financial company.