I find that I really wish that there was a sort of Law of Karma like there is for Thermodynamics. Just imagine what the world would be like if the harm you wished upon others was visited on you at the same time.
You want someone else to suffer? Easy! The only cost is that you get to suffer in the same way, proportionately.
(The proportionate bit is important: otherwise you might wish that someone else would lose a thousand dollars, which might mean them losing their house, while you have a cool $5k in the bank; you can tolerate the loss but they can’t! But if it’s proportionate, that means you’d suffer in equal measure to them: if they had $800 and you caused them to lose $1k, well, you’d be losing more than your $5k as well.)
Want someone else to get cancer and die? Well, you’re a LITTLE better off than them, now, because at least you have foreknowledge and can line up your burial ahead of time.
OR….. maybe you’d sit back and think “Do I really want someone else to suffer? Is it worth it, for real?” — my guess is that the answer would usually be a resounding “no.” At the very least, the ill-wishes you had for others would be more “annoying” than severe – you’d say things like “I hope their coffee’s too cold” instead of “I wish they were dead.”
It’s a pity this karmic dynamic isn’t a real thing. Instead, when you wish ill on someone else, well, you become an ickier, gross person… and that’s it, and the scum that lines your soul is easy to hide.