Why are ETFs low risk?

Could you please elaborate on the reasons why Exchange-Traded Funds (ETFs) are considered to pose a relatively low risk? I'm interested in understanding the factors that contribute to this perception, and how investors benefit from the inherent stability and diversification that ETFs offer. Could you also discuss any potential drawbacks or caveats that investors should be aware of, despite the generally low-risk nature of ETFs? I'd appreciate a comprehensive explanation that highlights both the advantages and any potential limitations associated with investing in ETFs.