If I was reasonably confident I knew better than you, how you should live, under what basis do I have the obligation to take away your agency to elect override your own preferences?
Under the norms of your society/culture. They obviously aren’t static, and can e.g. fade away, having lost to external competition (like vikings had), or change in response to internal critique (like how colonialism became discredited). If you would rather operate under some hypothetical perfect rules derived from first principles, then you will likely be disappointed, seeing how philosophy has for millennia utterly failed to discover those.
Under the norms of your society/culture. They obviously aren’t static, and can e.g. fade away, having lost to external competition (like vikings had), or change in response to internal critique (like how colonialism became discredited). If you would rather operate under some hypothetical perfect rules derived from first principles, then you will likely be disappointed, seeing how philosophy has for millennia utterly failed to discover those.