Owning 1000 satoshis/21M BTC is guaranteed to be worth 1000 satoshis/21M BTC 100 years from now, it can not be debased.
Every fiat currency (USD, GBP, CAD, AUD, etc..) has a denominator (aka max supply) that increases. Almost every fiat currency dies a horrible death in less than a century due to this inflation. 1 British pound sterling used to buy 12 ounces of silver but is now worth 0.5% of its original value and dropping. This is not lossless time/labor storage, the denominator is increasing rapidly as central banks respond to the crisis of the day.
How does a beanie baby look after 100 years without maintenance, no deterioration? How easy is it to counterfeit a beanie baby? The problem with your approach to criticizing BTC is you believe you can isolate the properties first. All the properties I mentioned and more work together in a synergistic fashion to create a lossless time/labor energy storage network.
>I should be able to create a new Bitcoin using the exact same technology because it's Open Source, and it should also be just as valuable, right?
This would be true if we ignored one of the primary laws of money, "hardest money wins". There can literally only be one hardest money, and capital will flow into it precisely because it is the hardest and acts as the best store of value. This is where looking at BTC as technology first leads you astray, it is in fact money first. Money will flow into one rather than the other BTC fork and the one with the highest hash rate will secure value better. The network with the highest hash rate will also have a huge incentive to expedite the death of the softer/less-secure money/network through 51% attacks and more... then consume its value.
Silver was the hardest money in the world until people realized gold was more scarce and harder to mine...silver turned into a shitcoin not long after that moment. Anyone that continued to hold silver after that point suffered a tremendous loss of value... hardest money wins in action. Bitcoin is now doing this to gold and every store of value on the planet thanks to better design.
>How do you even trade your bitcoin when there is no network for you to connect to?
This is P2P money first, just because it has now scaled to 10M+ users doesn't mean it can't run like it originally did, with 1 miner and 1 node. It can scale all the way back down to the size of whatever is required in your doomsday scenario. It will still be the hardest money in the universe in that scenario since all networks will be equally affected by the blackswan, so the people that do continue using it will appreciate its lossless storage and retrieval of human labor/time energy. We already have the blockstream satellite for transactions (Puerto Ricans were using BTC while banks were closed due to no electricity after the recent hurricane) and over the next decade nodes and miners will be put in space (probably by SpaceX and other large holders pushing for multi planetary human existence)... the network hasn't gone down in 12 years and after space nodes/miners are in place, the network will never go down unless an extinction level event occurs in our solar system. It is so well designed, it is already a space money solution.
I took another run at this because the longer you take to understand these concepts the poorer you will be. This may be among the most important information you could ever receive at this moment in history but requires knowledge in ~5 disciplines to fully appreciate... ~200 years ago I would've been doing something similar by telling you to convert your silver to gold before the price plummeted into a death spiral.