The purge is soo unlikely, that the reason behind it are so dumb. Like psychological, allowing people doing it more maybe allows them to resist more but on what basis of research does that come from?
And then what happens the next day? Wouldn't it be very stupid to have the law in the first place, since they may know who killed everyone. What happens to the theives and unlaw people the next day? Would they really let people get away with a selfless law the previous day.
But I would just stay in a zombie protected high level security.