You aren't really believing in math. Doubling the number of Bitcoin in the world is not blocked by mathematics (trivially change the constant in the source code), it is blocked by a consensus of humans believing in the artificial scarcity that a system robustly provides. For instance, if Bitcoin ever adopts post quantum cryptography, the math breaks - it is a technical fork. But, since a vast majority of participants (maintainers, miners and holders) will likely agree that it is a good idea this new fork will be named "Bitcoin" and everyone will be happy. Not math at all, rather a broad consensus among humans.
I'm not suggesting Bitcoin is a bad investment at all, but believing in it because it "is math" is not correct.
Most normal currencies are the same as bitcoin/crypto in that they are mostly digital but at least they have some mostly agreed upon value within their system. They don't need to be converted to another currency to find out which goods I can exchange for them.
The Dollar has an agreed-upon value of 1 Dollar per Dollar, the Euro of 1 Euro per Euro and the Bitcoin of 1 Bitcoin per Bitcoin. There are no agreed-upon values in any currency in free market. In socialism, they would dictate that a pound of butter had to cost 1unit of some currency. But in capitalist free markets, the value of a currency is always measured realtive to others things, being it goods (such as a standardized shopping baskets used for CPI) or other currencies or assets. For example, there is no way to determine if the dollar raised or fell - it always has a value of one dollar. But there is the DXY ("dixie") dollar index, where the value of the dollar is measured by its trading price with a basket of other currencies. Now if the DXY falls, you can say the dollar lost value. You could also say, the foreign currencies increased in value. It is always relative.
Plus, 100 dollars bought a whole lot of things 50 years ago, a lot less things 30 years ago, and today the same 100$ buy a lot less than that. There is no agreed upon value, it is supply and demand.
My point being, you can have two competing currencies and exchange between them. In Argentinas case, the currency competition was healthy as politicians couldn't conceal their bad financial policies due to the hyper inflated exchange rate for pesos.
Lightning uses so called hashed time locked contract (HTLC) between nodes backed by bitcoin 2-of-2 wallets, with punishment options baked into the transaction script if people try to unilateraly reallocate funds from the channel. The channels between nodes form a payment network, where each node forwards funds (in return for a small fee).
To use a metaphor: bitcoin is the gold, lightning are green dollar notes with a guarantee to exchange those notes for gold anytime - just as our monetary system was before 1971 when Nixon broke that promise. Lightning is built in a way that it is decentralized and that promise can never be broken. And you can send those notes via the internet in sub-seconds.
You still don't grasp lightning fully, and I totally understand because it a complex concept. It is not its own crypto, it is not a token, and lightning does not even use a blockchain. It is a layer 2 network, meaning it builds upon BTC and requires BTC node to run (to monitor the new blocks and publish transactions). So lightning cannot replace bitcoin, it augments it.
Would you agree with me that lightning 'stretches' each BTC transaction by using clever tricks ala. aggregation, checksums, hashing, etc.? I buy that this scales the number of transactions dramatically, especially between a limited number of parties. It might be that this is stretches far enough be make BTC useful as a currency, but I remain very doubtful of that. If that is indeed the case, it seems that BTC has managed to fail as a currency for other reasons.