To be clear, I like the idea of making something really useful and being rewarded from bettering other people's lives. I don't doubt that if you make something really useful for the world, you can gain a lot from it.
But when people talk about fairness, (I assume) they're usually thinking about the successful scammers, predatory practices, people not contributing to the world yet profiting a lot from it. They may also think about "essential workers" who, in contrast, may live paycheck to paycheck.
It becomes blurrier to me when I think about who "deserves" what.