Define justifiable. I would agree with “unfair.” Life is not fair. Is life “justifiable” to you? In nature, there are predators and prey, is that “justifiable”?
I like to simplify my thinking too, but your view seems inherently suppose almost superhuman discernment, that you (or other humans individually or collectively) can judge what is justified on a case by case basis without any concrete principals or criteria, and without bias! Doesn’t seem simple to me at all! How to distinguish the bill gateses from the other guys is a problem as old as civilization. There is more law and tax code written on this than you can ever hope to capture in your thinking. Ignoring policy and centuries of human knowledge isn’t “simple” as much as it is ignorance.
People who continue working to expand their impact even when they don't need to are rare.