Bitcoin is a line of code. It technically can be adapted, but is very very unlikely to happen now. It would need 51% consensus, which is basically impossible at this point. The larger the network grows, the more decentralized it becomes.
This is a feature however, not a bug. I want to know what I am investing in and what it will be in 10, 20, even 100 years from now. The feature will allow for Bitcoin to become the base layer of money for 8 billion people. To use an analogy, is it a good thing that 4 always equals 4? Of course it is. It allows for use to make computers, bridges, fly an airplane, and etc. What would happen if one day President Biden wakes up and says 4 now equals 5? All of us would have to reengineer everything we have already built. This is what happens with our current monetary system. Small groups of people (Central Banks/Governments) are able to change and manipulate the money, which has 1,000s of negative downstream effects. This has been a major issues countries around the world, for example Lebanon, Turkey, Egypt, and etc.
The fact that Bitcoin can't be changed by any government, group, or person, is one of the reasons why it's so valuable. The overall point of Bitcoin is to have a sound monetary policy that is slow, consistent, and provides the base layer of society for 8 billion people. I want it to be the same today, tomorrow, and 100 years from now. The objective is for a person living anywhere in the world can be freed from oppressive regime and build a better life for themselves. You can't do that if the government is screwing up the money. Money is the base layer of societies. Americans just haven't had to think about it because it's been relatively stable the past 40-50 years.
Bitcoin can handle more than 4 transactions, but you're correct on the overall speed. It can handle far fewer transactions than Visa and etc. It was designed that way. In order to solve the Byzantine Generals Problem they need nodes to be able to verify transactions. The larger the block sizes (allows for more transactions) the more expensive it would becomes for nodes to verify the transactions. Basically, you would need a crap ton more of computing power and energy. This would centralize the network over time and make it fragile. Small block sizes means anyone (yourself included) can run a node and verify the network. It makes Bitcoin decentralized and anti-fragile. Once again, this is a feature, not a bug. Bitcoiners want slow and predictable. The goals are a sound decentralized monetary policy for the world. This is another innovation that allows for it.
The 2nd and 3rd layers are will the Visa payment type of systems will be built. A good analogy is to think of Bitcoin like the internet. In the 80s and 90s it had very few use cases (compared to today), but eventually people built 2nd, 3rd, 4th layers on it. Someone invented browsers, which led to search engines, which led to websites, which led to etc. The same thing will happen with Bitcoin. There are people already building those things. They'll catch on over time as more and more people use those "apps". I linked Mallers who founded Strike. Really cool due.
The inventors pseudonym is Satoshi Nakamoto. I linked his wiki if you want to read more.
https://en.wikipedia.org/wiki/Satoshi_Nakamoto.
Nobody knows who it is or if they're alive. There are 1 to 2 million coins that are probably lost forever. You can check the wallets on the network and they haven't moved for years. If Satoshi did still control them and chose to sell them, good. The market would absorb them over time and become more decentralized. I'd love it if he dumbed a million coins on the market. The price would drop and I'd get cheaper Bitcoin.
Once again, it's a feature you can't go back and change the network. If you lose your coins (forget your seed phrase for example), they are gone forever. There are numerous other ways to obtain Bitcoin if you're not comfortable with self custody. You can go through exchanges (Coinbase), ETFs (retirements), PayPal, Venmo, and etc.
The question is what is Bitcoin? Is it a currency? Is it a store a value? Is it a network? Is it the new base layer monetary system for the entire world? Or is it all of them? I don't know for sure, nobody does. I think it will become all of those things, which is why I won't shut up about it.
I’ll add, it's clear at this point its a new asset class and at the very least it's a store value that is much better than gold. Gold is currently a 16 trillion dollars asset class. Bitcoin is just over a trillion. I'd strongly advise reading The Bitcoin Standard. You fundamentally misunderstand what Bitcoin is (I don't mean this in a condescending way).