If everyone on earth had an equal share of all the money that currently exists, what would that look like? Would everybody be middle class or would we all be poor?

When I grew up in communist China, we had something quite similar to that--*everyone* was issued what was called "liangpiao" roughly translate to foodstamps.

It was really really even, unless you are among the top 5 levels of communist party or government officials, every adult got the same amount of stamps (about ~35lb of carbs and 1–2lb of meat a month). Children got less. Stamps are not necessary for farmers, the “gongshe” roughly translated to “public society” will decide what everyone can eat (because most of the produce needs to be submitted to the country)

It sounds insane now, but the carb stamps were also separated to rice and wheat.

First thing people noted was those who were 6 feet and 200lb might need a little bit more food then someone 4 feed 6 and 80lb. (Yeah, something as common sense as that was completely ignored by the "everyone has same amount" mentality.)

So some kind of underground trade started—public trading of the stamps were prohibited.

Then, there were people liked flour, others liked rice. The solution? More underground trade. And unsurprisingly in communities where more people like rice than flour, the rice stamps would commend a higher demand hence the trade tilted towards rice.

So, first of all, everyone has the same amount of resources (either money or food) is not "fair" - people just come in all sizes and abilities! We used to have cloth stamps as well, and being tall was something parents cursed about their kids, because that means less cloth for other family members. And yes, I used to wear ”long sleeves” that ends at my elbow, and I’m not even tall—i was actually lucky that my grandma used to work in a clothing factory as a tailor, otherwise I might not even have enough cloth to cover my shoulder!

Second, there would not be a need to "even things” if the "things" are abundant. The fact that we needed to have even food distribution was the result of not enough resources to satisfy everyone — and because the median is defined as value at 50% quantile, yeah, middle-class means ~30USD monthly income for a double income family. Despite technically everyone is “middle class”, I’m not sure that’s the “middle class” people wanted to be in.

Third, no one had what they really wanted, like the rice and flour issue, people were assigned thing they don't like or need, but not enough of what they need—because everyone got the same, but not everyone want the same things. Inevitably, people will start to trade, even if it is forbidden. So this even distribution won’t last.

Fourth, we were not producing anything valuable. Because of the extreme averagism, no one felt the need or incentive to produce anything other than what the government ordered them to do (which you can imagine wasn’t the most valuable), because they didn’t got to keep any part of the value they create, the government did. This exacerbated the porvety issue because people do not make effort to make a change by creating value.

The attractiveness of the "evenly distribute" wealth is that the majority of people thought they can take money from those who are richer, the reality is most people actually will end up "been taken from" because the government doing this redistribution has extremely high overhead, most of the wealth are consumed by the redistributing government, so the amount available for the people to share was not only much smaller than people thought, but also was a one time trick, cause people would stop producing value after the forced redistribution, hence nothing to redistribute thereafter.

To be clear, to reach extreme equality money-wise, there will have to be an extreme inequality in power - the power to forcefully taking resources from some and distribute to some others, and this inequality in power is very costly to maintain and the existence of it cost society to hold back innovation and creating value.

While inequality in money is undesirable, inequality in power is thousands of times more scary and destructive.

No matter how appealing some preach it superficially, Having the government redistribute wealth is like using nuclear weapons to stop gun crime - a much worse thing to replace a bad thing