As an ETF is a product designed and managed to reflect the movement of a stock index, if the index goes up or down, the price of the ETF also fluctuates in proportion to such changes.
Therefore, ETFs are relatively safe investment products because the yield is determined by the conditions of an overall market or a specific industry with relatively low risks and price volatility compared to when invested in individual companies.
Decision-making on investment is easy for ETFs, as it is making an investment on market direction which does not require information and analysis on individual stock. Since they move virtually the same as stock indexes, it is easy to identify the price movement without checking the corresponding ETF prices.