But the whole point of bitcoin is that it solves the digital double spend problem you mention.

Let's zoom out and talk about the basics of money (some of which you maybe already know). Okay, so in theory we could use anything as money. In some ways, everything is money, but in a range from terrible money (e.g. air, TVs, food) to excellent money (TBC). The laws of nature ensure that we end up using the things that work best at money as money.

Money needs to perform the following three functions:

- medium of exchange

- unit of account

- store of value

and in order to perform those functions, the thing we're using as money needs certain fundamental qualities which are:

- good divisibility

- good portability

- fungibility (equivalence/interchangeability across all units)

- robustness

- easily verified/assayed

- scarcity

These properties are well recognised, and if you take a look at gold, and compare it to predecessors such as shells, beads, Rai stones you can see why it was a stronger money, and why it became economically valuable - the world chose it as the best money and to store it's economic value in it.

But gold wasn't perfect, it still wasn't particularly portable, or divisible. As technology improved, it's not so easy to verify (e.g. tungsten wrapped gold?). It's also fairly easily stolen from us and so we naturally moved to store our gold with banks who could not only provide a secure location, but would give us paper receipts in return that evolved to become an excellent form of money whose value was bootstrapped into existence because it simply took on the value of the gold it represented.

This paper money was better at being money than gold in many ways - more portable, divisible and arguably more fungible and easily verified. However, over time it failed in one particular area: _scarcity_. The banks realised they could get away with printing more and more of it without people realising or being able to stop them. Ultimately it resulted in central banks like the Bank of England, the Fed etc who are almost freely printing infinite amounts (and charging interest on it). It continues to survive as the best money because a) most people don't realise the scarcity issue and simply see prices going up as some natural phenomenon b) even with the lack of scarcity, it still makes better money than gold especially now it's almost all digital.

The breakthrough that Bitcoin made is that it actually solved the digital double spend problem you mentioned - a previously unsolved problem in computer science. Here's an simple explanation how: https://youtu.be/CoGxakp1_3I?si=wvCxUZtUtS-jC9DX&t=694

Sure you can fork bitcoin, but no one is going to care about your new money/blockchain. If you stick a picture of a dog on it, there might be some fun/novelty value, but Bitcoin has massive network effect, and anything that wants to beat it will need to be substantially better and in a way that bitcoin won't simply adopt itself.

This means that for the first time in human history, we have a digital money that has better fundamental monetary qualities than gold and quite likely fiat too (depending on how higher-level networks such as Lightning scale). We've got perfect digital scarcity in a liquid asset and this is something that mankind has never seen before and most people aren't ready for.

> "I think claiming anything invented today will never be surpassed is unlikely to be true."

It's so good that it's very difficult to see how it will be bettered (in the physical and digital realms at least). It can of course also evolve as time goes on.
Based on its fundamental qualities compare to gold and fiat (and real estate, and bonds, and cRyPtO etc), it's very likely that it will suck in all the stored economic value in the world over the coming decades/centuries.