And I understood then that even if you constructed an argument showing that something was the best course of action, Nature was still allowed to say "So what?" and kill you.

You can actually do what actually is the best possible course for you to take and reality can still kill you. That is, you can do everything right and still get buried in shit. All you can do is do your best and hope that cuts the odds against you enough for you to succeed.

It helps if you also work on making your best even better.