Duty to retreat isn't 'insane', but rather a different perspective on how much vigilantism a society (or state) is willing to tolerate.

I don't think it's that insane to retreat from certain situations and leave things to law enforcement, depending on the situation. For example, it probably is better to let competent, trained law enforcement marksmen deal with complex tactical situations like hostage crisis, rather than trying to engage armed criminals in fisticuffs on your own in a standoff (if you are able to duck or retreat to safety) and let the trained marksmen with body armor engage in gunplay (or deploy non-lethal force like taser, beanbag, etc.).