What would happen to our society if a maximum income was implemented?

This is sort of the case when income tax is high. Businesses pay lower wages but then supplement income with a cheaper alternative (like a company car). I suspect you'd see more and more of the highest earning people having greater supplementary benefits, like a house, yacht, garage full of cars, holidays, etc.

All that said, we will always have high earners because the high earners control how the world is.

Tyranny would start creeping into all aspects of society, little by little, until the government controlled it all.

The end of advancement. No incentive to create new idea's.

I refer you to what China was like before the economic reform of the 1980, when such limits were in place. It was third world basket case economy.

We are humans. We respond to incentives. A tiny, micro- proportion of business leaders get ludicrous payments, but that's the choice of shareholders. All they do is reduce their own dividends. Idiots.