Time goes on, machines get cheaper, the surplus doesn't go to the inventor but to the people buying the machines. So wealth turns into more wealth.

Even if a person can't provide productivity "on their own", productivity per person increases, and it's bad for that to be tied to an increase of wealth inequality.

And trying to have everyone invent solutions sounds like a weak justification for a broken system to me, along the lines of the temporarily embarrassed millionaire.