LACK

Your success doesn't mean someone else's failure because there is enough to go around. 

Success is not a finite quantity and you don't need anyone's permission to get it.  Living a small or meager life doesn't mean that you're leaving opportunities open for others, first because it's not your responsibility to do so, second, it's a copout rationalization, and third, the reality is that the more successful you are, when you're living the best and biggest life that you can, that's when you're also able to make a real impact on others.