I've Been Saving 500,000 Won a Month for 3 Years, but I'm Not Sure Installment Savings Are the Answer

At first, I thought I could just keep putting money into installment savings, but seeing interest rates drop and prices rise makes me wonder if that's the right move.

People around me tell me to invest in ETFs, but if I take a loss, I feel like I'll lose my mind. Would it be better to put half in deposits and half in ETFs? I'd appreciate some advice.