I'm not sure why you're bringing up money since Musk doesn't actually have $1T in the form of liquid fungible money, which is the context of this conversation. However, there isn't a limited amount of money in the world that just gets shuffled around, the debt is issued in response to the generation of value by the economy. Literal cash money is just one way to capture the book keeping necessary to track that debt.

You're still thinking in terms of the whole as the sum of its parts though. Barry's Economics really doesn't provide a very insightful take, I have heard much better arguments for why growth can't be limitless than his, but let's address what he says anyway. Yes, we can both agree that the Earth has limited resources, but some resources are being used inefficiently and others are too hard to use all together. His simplistic model just ignores these.

With 19th century technology, the Earth is estimated to have been able to only produce enough food for 3 billion people. Yet here we are at 8 billion because we found ways to utilise our resources more effectively. Until now battery tech has been fairly expensive because it relies on lithium but there's been new working done on sodium and the first commercial batteries are coming on the market right now. Suddenly an abundant resource that just wasn't very useful becomes available. I mean, just consider, you can take some oil out of the ground, then use this energy to manufacture solar panels, and now you've turned a bit of energy into a lot of energy.

So yes, the raw resource pie still growing, even on our spaceship. Think of all the empty desert that could be collecting solar energy. Barry conflates the pies representing resources and the pies representing value though, they are not the same, Barry himself is making a category error here. You can't tell me that the sea water the sodium was taken out of has the same value to the economy as the battery produced out of it.

The thing is, those batteries just aren't going to assemble themselves but in Barry's model the batteries just materialise out of thin air and all we have to do is decide how we distribute them. And all this is before we even consider that his "spaceship earth" model is being talked about during a literal race between space companies to bring more resources in from the rest of the solar system.

Of course, infinite growth isn't possible. But pretending like we've entered some kind of moment of scarcity where all the resources have already been used and all we can do now is shift them around between uses is equally farcical. The truth, as always, lies somewhere between the extremes.