How did Chaos Orbs become *the* unit of currency?

New to the game, apparently the chaos orb effect is usually undesirable. How did chaos orbs become a unit of trade?

Usually something has an intrinsic value if it is used as currency.

Did someone just "decide" to use it as such because it was sufficiently rare and it wasn't being used for anything else?

its intrinsic value is how its used for craft and for zana mods etc. they have value outside of trade, and they're common enough to be used for trade.

people chaos spam craft all the time. it can be very effective.

There are a few reasons.

-Chaos orbs are definitely useful! If nothing else, you need to use them on maps later in the game to make sure the mods are suitable for your build and sufficiently rewarding. Chaos spamming is also a viable method of item crafting for some item types. The important thing to note is that you often need them in bulk, rather than just small numbers.

-Chaos aren't completely trivial to get, because there's no way to obtain them besides drops and the chaos recipe. Compare to something like jewelers orbs or alterations, which are easily gotten from selling random item drops. There is also no NPC vendor that sells chaos.

-Zana's mods require spending multiple chaos per map, and doing so is generally considered mandatory for high tier mapping.

Chaos weren't always the number one currency. It used to be a lot more fluid early on in the game's life, and people used to be a lot more accepting of equivalent currency. In particular, GCPs used to be worth about 3 chaos and were a common trading currency until the 20 quality gem recipe became widely known. But it was really Zana that cemented chaos as the primary trading currency, because she forces high level players to always have a stock of them and continuously use them up.

I use Chaos quite a bit to change stuff on maps, and I'm sure others do too. You need them for master crafting, along with other things that you may want bonuses to be changed.

Chaos just got that rarity to them that they are still rare, but at the same time, not so rare that you can stock them up.

There are still a lot of people that use other things for trade, like Chisels when trading maps. Chisels and Alchemy seems to be the go to currency for map related stuff.

other very popular and alternative currency to chaos are vaal orbs, cartographers chisel and alchemy orbs. once leagues go on for a bit of time these currencies raise in price and desire due to their attachment to map crafting.

in any game without a dedicated currency, something common but useful can easily become currency.

In d2, it was SOJs (common because duped), and then 'High Runes' (again because duped)

It's very hard to trade an item for another item, because you have to find 2 willing participants for that specific trade. When currency is introduced, you may have to do an extra exchange, but the amount of people willing to do either exchange increases drastically.

It's also kinda rare, but common enough to be useful. Add it's uses in Maps, and ease of getting via Chaos Recipe, it's worthwhile.

Exalted is too rare, and too valuable for smaller level transactions.

Alchs and other currencies are Ok, but if your picking up gear worth and Alch or less, your wasting time and space picking up and trying to trade.

well you look at the most used currencies in large quantity and its

alteration
alchemy
scouring
chaos

by definition chaos is at least alch+scour. so its the orb with most weight behind the value amongst the common ones. that and ofc zana mod as well. you cant alch scour zana mod but you can always trade chaos for at least alch&scour.

Because Zana mods and the chaos recipe, everyone can get chaos in a steady stream with the recipe. Not like exalts that you need to get the drop.

In the beta, chaos orbs weren´t the only currency used for trading by far. In fact, a chaos orb was rather a high value currency item and was not thst easy to obtain as today. I remember we traded usable items for alchemies and if something was actually worth a chaos or more, that was already rather uncommon. Exalts were sth people like myself dreamed of.

Now don´t forget there has also been a huge deflation of currency all the way down from mirrors. It´s a logical process, and if you just have a look at standard league, we are almost at a point where people don´t seem to bother for chaos trades any more at all.