Many of us think its 'brave' and 'correct' to say "all lives are equal value" in the moral sense. Its a 'sexy' thought to have as it seems liberal and its simple, but it is ultimately wrong.
Our actions are what define us, so a person who performs good/selfless actions that benefit others should be defined as higher value than a selfish murderer/rapist.
If lives were equal value then taking the life of a child would be equally as bad as taking the life of an 80 year old - but most people do not think that way.
Your value (in the moral sense) should simply be a function how much good you provide to the world. This leads to the difficult issue where because we can in fact buy "good" (by buying anti-malaria nets for children for £5 a pop) you find that those born into wealth have a higher capacity to perform "good" and therefore, on average, have a higher moral value by this definition.