Most Helpful Guy
That's not really how people work, so the Purge is super impractical (and a bad movie). People who perform crimes typically do it for two reasons. Either they're desperate and the crime would help them in some way, or they enjoy performing those crimes and continue doing them. Making crime legal for one day each year won't stop those things from happening.
Most Helpful Girl
No, I would not. Putting ethical arguments aside, implementing a free-for-all, get-your-crime-on day would just be ineffective from a crime prevention standpoint and problematic from a socioeconomic standpoint.
For one, it would increase taxes and make the cost of living go way up. The infrastructure damages (as most people that participate would be raiding, stealing, and vandalizing) from that one night would require lots of funds to repair. People--home and business-owners alike--would be spending considerable amounts on weapons, ammunitions, fortifications, and security systems. If you value your life and property, you would HAVE to spend on these things, whether you choose to participate or not. Sure, this would increase business opportunities for such manufacturers and the subsequent clean-up crew, but in the end, that would create even more of a wealth gap between the rich and poor. Essentially, there would be an entire industry built around that single night. As such, a good chunk of the places which participants envision looting and wrecking would simply be untouchable. Similarly, a good chunk of the people you have a personal vendetta against would probably also be untouchable (if you can afford to be secure, chances are, the enemies you've made in your day-to-day life can, too), or simply very well-hidden. You'd probably have hired mercenaries policing the streets, too.
That brings me to my crime prevention standpoint. Most serious crimes, like homicide, are not premeditated; they're a heat-of-the-moment/lapse of judgement type of scenarios. A Purge night is not going to prevent non-premeditated crime from happening the rest of the time. Furthermore, the vast majority of crimes are not violent, and are not spurred by a desire to be violent. The majority of criminals are not psychopathic. Of those that are, do you really think that a single night out of the whole year could get them to restrain their violent impulses? Furthermore, how many people would even see it worth the risk to go after someone on a night like that? And lastly, there might not be legal ramifications for one's actions, but there sure as hell will be social ones. If I'm your next-door neighbour, and I go out a murder spree or see you dead bodies being carried away from my house the next morning, are you going to look at me the same way the next time we cross paths? I don't think so.