Is it smart to just invest in ETFs?

Is it really a wise decision to solely invest in Exchange-Traded Funds (ETFs)? On one hand, ETFs offer diversified portfolios with low costs and easy access, appealing to investors seeking simplicity and convenience. However, are we overlooking the potential benefits of a more diversified approach? Could investing in individual stocks or alternative asset classes provide additional returns? Also, how do we factor in market risks and volatility when considering ETF investments? Is it possible that a solely ETF-based portfolio may not be able to fully capitalize on market opportunities or protect against potential downsides? Is there a balance to strike between convenience and potential returns? And ultimately, does investing solely in ETFs align with my personal financial goals and risk tolerance?