system
Given the following post, respond as if you're commenting on Reddit:
human
CMV: After a person has earned a certain amount of money in a year (say, north of £5,000,000), they should be charged at a tax rate of at least 80%

About half of the world's wealth is currently held by the top 1% in society, a significantly higher tax rate for the very top earning members of society will both prevent more money being hoarded by them, reducing the wealth gap between the ultra-wealthy and the poorest people in society, and it will mean that billions more will go towards tax which can also be used to build up the economy and help the less fortunate people.

When someone has passed a certain threshold (not necessarily £5million, but that seems like a reasonable number in my opinion) they will not really need that much more than that, they wouldn't really be able to spend that on anything other than things that people would never really need. Plus, why should people be able to have millions that they can spend on extravagant items when some people cannot even afford a roof over their head, or food to feed themselves/their family.
gpt
What you're missing is the presumed link between productivity and compensation.

Elon Musk is responsible for PayPal, Tesla, and SpaceX, right?

What if after PayPal the government told him "Alright there Elon, you've made enough money, we're taking the rest from here on out"? Even if he's not the kind of guy motivated by money, that means he'd have no resources to fund those other projects. Those other companies wouldn't exist because we decided to stifle innovation. 

Some people make a thousand times more than others because they're doing a thousand times more for society.