The short answer to your question is “negative externalities” and “collective action problems.” Sometimes we can’t just solve a problem by ourselves, either because no one person has a rational incentive to change their behavior, even if everyone would be better off if we all did (see, eg Prisoners Dilemma or Tragedy of the Commons), or because the actions of third parties are creating problems for us (see eg pollution, disinformation, systemic risk in the financial sector, etc).

Sure, start the inquiry at home. See what you can do differently first. But don’t let this idea that you just need to “clean up your room, bucko” blind you to the reality that some problems require collective action to solve, and if we wait until we have our own individual lives perfectly in order before we try to solve them, we’ll be waiting forever.