As much as people enjoy an eye for an eye when it comes to getting back at people, the mental damage already been done and its only so much you're willing to do within legal boundaries before you crack.
I think revenge is fine on smaller scales, but imagine holding a grudge so long its all that fuels you and your mind becomes dull to everything around you. It really eats away at your soul, but at some point you either come to terms with shit that happens, or you finally fuck someone up sideways and its no guarantee you'll feel satisfied afterwards.
If your gf cheats on you and you go off and shoot her, the guy, half her family, and the dog its still no way for that guy to unfuck your bitch and now your life has completely shifted cause you couldn't hold that L and went into a fit.
I'm not saying dont stand your ground but its so many long term ways to get "revenge" without some instantaneous form of comic book brand justice.
Also little bits of revenge like some rudeness or smug comments can be solved by standing your own ground and not require so much effort. A quick witted comment that leaves someone embarrassed cause they thought they had you ruins their day and they generally back off unless they're retarded