Jude: By your logic, all of us are at the same time helping people by living an extravagant lifestyle while other people are able to enjoy life on other parts of the planet.
The difference being that doesn't make any sense
I'll explain it for you, since you're probably the kind of guy who has troubles with the "half-full, half-empty" logic:
Here's your statement:
All of us are already killing people by living an extravagant lifestyle while people are starving on other parts of the planet.
Since "all of us" are killing people on other parts of the planet, it would follow that we are, at the same time, saving other people at other OTHER parts of the planet. You can't have a glass half-full without it being half-empty.
To elaborate: For every African kid we starve to death because of overpriced grain export rules, a Chinese kid gets to eat meat with his rice as his father got employed at a new grain processing facility thanks to the high grain prices. For every poor American textile worker who was fired and is forced to sell his home, there's an Indian family of seven who won't starve to death thanks to new textile operations in their area.
People love to overlook the good effects of a policy and focus on the bad. Besides, I'm not sure how my buying a new computer kills people. If you want to calculate the opportunity cost of every action (You COULD have used that money to save 5 children), then I have this to say: if you weren't born, someone else would have gotten the 4.3 million total US dollars in personal finances, government expenditure, and additional expenses that was spent raising you; money that would have been well spent inlaying gold platings for my swimming pool instead of raising an ungrateful brat I might add.