Simpsons meme aside --

Those with currency can have significantly more options than those without it. I'm of a privileged state where if I wanted to drop everything and visit another country for two weeks, there's nothing stopping me financially. Not many people have that luxury.

Makes it easier to buy food and pay for rent.

My landlord doesn't want to barter for goods and services on a monthly basis.

Can be exchanged for goods and services

Because it's very difficult to get things you need to live solely through barter. Many trades are very niche, and an economy that uses money allows those trades to continue being viable parts of society.

Like, think of plumbing. If everything goes well, you don't need a plumber. But when you do...you really need it. Now imagine being the plumber who wants some bread and eggs but the farmer has no problems currently that needs the plumber's skills. Plumber can't eat, leaves profession, there's now no plumber when the pipes do break.

Obviously, the next thought here might be, "Well, why doesn't the plumber say if they get eggs and bread now, they'll come and fix your toilet later if needed?" But that sort of re-invents credit, right? "I'll trade 3 future plumbing problems for 3 boxes of eggs now." If you have that, why not money?

So basically, money is very useful. It can be traded for many things you otherwise wouldn't be able to get if you were only able to offer as barter a specific item that might be rejected by the other person you want to barter with. Money is a "universal" trade good, and it's also easy to store (you don't have to have lots of physical room to store your Universal Trade Good).

The BEHAVIOR of people surrounding this very useful thing can absolutely be suspect, depending on the person (greedy sociopaths hoarding wealth)--but that's a human thing, not because money is innately a bad thing. It's a social problem, not a technology problem. You could totally have a greedy hoarder storing up a non-money trade item too...see people and toilet paper/sanitizer during Covid.

Here's my take:

1. We're built for about 150 relationships max (Dunbar number), and yet we benefit from cooperation above that threshold. Rather than make it so we have to have a personal relationship with everyone who could possibly benefit us, we accepted a ramped down version of relationship we call "transactions". This is a very weak replacement for a relationship, but it is a sort of "micro-relationship" in that for a brief moment two people who don't know each other can kind of care about each other during an exchange. Through specialization, we can do something well that doesn't just benefit the handful of friends and neighbors we have, but tens of thousands and possibly millions of people via transactions (e.g. a factory, starting an Amazon business, etc.)

2. There is a process called "commensuration" in the social sciences, where people start to make one thing commensurate with another, even in wildly different domains. For example, to understand the value of a forest and to convey its importance to decision makers we might say "this forest is worth $100 billion". It's kind of weird to do this (how do leaves and trees and anthills and beetles equal imaginary humoney?) But slowly, over time, we have made many things commensurate to dollars at various scales. (I don't think this is a good thing, but it does have benefits). In short, more and more things that were part of an implicit economy of relationships (e.g. can the neighbor girl babysit tonight?) have entered the explicit domain of the monetary economy (e.g. sittercity).

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IMO, in order to participate in the huge value generated by this monetary economy, people sometimes lose the forest for the trees (so to speak) and forget what really matters (e.g. excellence of character, deep relationships, new experiences, etc.) because it seems like we might be able to put off those things until "after" we square away this whole money thing first. But maybe "after" never comes--and the hollow life of a consumer capitalist drains the inner ecological diversity of a soulful life.

Consider what we used as currency before it was currency. You would have to barter before, which was inefficient. Common currency saves you and everyone involved time. Instead of having to barter for every item, which would also require you to do carry all of those items, you can just pay with currency now.

Because they represent a resource, concrete or abstract. Currency is easily exchanged, either for other currencies, or for goods and services. This allows for a lot more opportunities than hauling around a swarm of sheep for bartering at the car dealership.

Modern society is only possible because of global trade networks. Global trade networks would never work without currency. If a person spends all their day fabricating metal sheets they need a way to buy bread to feed their family. Otherwise we'd all be back to farming our lives away.

There is also a meta discussion here on liquidity (how easy it is to exchange something). People want currency because it is easy to exchange. Your landlord might be okay with getting paid in a mix of gallons of milk and some cuts of beef, but most will not. Trading for "non currency value" is not uncommon. You might get paid with stocks depending on your work. If you buy a car you might trade in your old one.

You can either barter or you can have currency. Currency is the means through which the economy functions. You need something abstract to indicate value. That's currency.

In a post-scarcity society, when everyone could just get everything they wanted whenever on a whim just because, we could get rid of it. Could. Probably wouldn't. That society is a fantasy. But it's nice to dream of.

It lubricates economic activity (not a lewd joke). It makes it easier to exchange shit, which leads to a more robust economy. Would you rather barter?

Those are 2 very different questions

Food, water, sex, security, shelter. This are the major factors that drove human behavior. Currency is only useful in that it can be used to secure the other things.

Nobody is lusting after a hyperinflated Zimbabwe dollar.

Maybe it's not as essential as one is led to believe. The book Debt by David Graeber deals with the very question you asked. I highly recommend you check it out.

I can't really summarise it well since I haven't finished it myself, so maybe peruse the Wikipedia entry. But the first couple of chapters try to answer your question

https://en.wikipedia.org/wiki/Debt:_The_First_5000_Years

Every exchange between people requires an exchange of value. If we both agree on a common "thing" as a representation of value, we can be more accurate and flexible in our transactions.

Barter was never a thing in daily life. No anthropogist found evidence for that. Trust based systems were used, but those don't work well when they population increases and interaction with strangers happens more. That's where currency takes over.

Why currency is the most important thing right now? Because currency at the moment is status and many people seek a high status on society.

Currency is an energy equivalent in human society. I'd say our current ridiculously exploitable system with greedy for profit banks, rampant credits, tax havens, exchange rates manipulation, dividends and stock market micro trading leaves a lot to be desired, yet it is still incredibly convenient and relatively stable even with all the major crashes. Beats barter that's for sure.

We are focused on it because life itself is based on burning energy to sustain itself. Any plant would be happy to get more nutrients and sunlight like every animal would gorge itself to get some of that fat on their bones. It doesn't matter that it's sometimes to the detriment too - it's just wired that way in the DNA, because scarcity is way more common than abundance and if this balance crumbles then it's just a matter of time before abundance turns to even more scarcity due to overgrowth/desertification/overpopulation.

Kinda like when an AI is overtrained on one thing that wasn't really correlated to its original goal, we've attempted to create a system that organizes collaboration between people; were now so overtrained on acquiring wealth that some would rather the planet burn than risk acquiring slightly less.

Its similar enough to a trail of ants in a death spiral; the same essential survival instincts that their society depends on, now nefariously dooming all involved to a slow starvation.

That being said similarly to the ants most of the populace will do the average (as it's what's kept us alive this long so how could it harm us?) And continue the spiral, but if one individual is able to reconnect the spiral to the main pheramone train the entire death spiral may be avoided

We live in capitalism

Because it gives the ruling class something to hold over the poors so the rest of society is so terrified of becoming poor they forget that they're being used as literal slaves for the state