murder is murder

For me it's a case of where the end justifies the means. While murder is terrible and I'd personally feel bad if I had to take another life, it'd be for the greater good of our species (as well as every other lifeform on this planet) if the world was suddenly ridded of a billionaire or two... or more...

I do recognise that this is a slippery slope in justifying homicide, but what is the alternative?