The 2nd layer always maps to the settlement layer as in you're still transacting in Bitcoin, you just don't broadcast the signed transactions to the whole network because you expect to continue your transactions.

You can use eth or any of the thousands of other crypto-currencies, Bitcoin benefits from being the most secure and also having the largest network effects due to being the earliest. When it comes to money, security is the most important thing and Bitcoin offers the most secure settlement layer.

If a credit card is the example of a layer 2, with dollars being the base layer, would you say that dollars don't matter then, and the only thing that matters is the layer 2?

You have it backwards. With credit/bank cards the second layer is dollars that we're transact in. If financial institutions decided to settle amongst themselves with commodity stocks, government bonds or FedCoins would you even notice? It just happens that in the US dollars also make a good settlement layer.

Good point. Would I notice? Yes, most likely. Would people who don't pay attention notice? No, probably not.

I was giving an example that Bitcoin and layer 2 solutions are related, similar to how dollars and credit cards are related. My point was if the layer 2 networks have value, it doesn't mean Bitcoin doesn't have any value.

Even in the cases you raise, dollars still probably will have some value. I don't see the dollar collapsing any time soon.

Is Bitcoin the best settlement layer? I'm not sure yet. IMO, Bitcoin / cryptocurrency in general does have some value since it is enabling new technologies, like layer 2 solutions, to be developed, when they otherwise would not have been. I think new technology is valuable.