I would invent a way to reach the hearts of everyone who is evil, or thoughtless, egotistical, or otherwise disconnected from humanity in general. My invention would not only benefit those who seem to think that everyone other than themselves is unimportant, or disposable. It would benefit everyone.
My invention would be able to not just to get inside their head, but would reach their heart, so as to change their feelings, helping them become loving, caring individuals, so they would no longer think only of themselves. They would be able to learn how greed and only thinking of what 'they' may want isn't always good for anyone at all.
This invention wouldn't be something that just turned people into unthinking robots, without a mind of their own, but it would remove any recollection of any bad that may have nudged them into the hateful path they may have been following which only leads to destruction, and hate.
To help everyone enjoy life, and being together, sharing good times, and good things that life has to offer. It certainly wouldn't be just a facade, but would really make things better for everyone. Everyone would then be able to be understanding, and caring of each other, instead of only themselves.