It does imply that sandwiches are not necessary. I’m not sure what else you can draw from a comparison between an abstract concept and physical expression of one—you certainly didn’t materialize the expression out of thin air.
I can use raw ingredients to create a sandwich too, and if we prefer the each other's sandwiches more, we can agree to trade sandwiches.
Was anything actually created during the trade though? I think that's what he's getting at. An economist would argue yes, value was created, but it's an abstract concept at best, a bit made-up at worst, because at the end of the day it's the same two sandwiches.
"Wealth isn't real" is a pretty radical take though, and I'm not sure how productive it is to contemplate because you'd have to entirely throw away the concepts of personal property and money before you can get there.
> at the end of the day it's the same two sandwiches
No, it isn't, because the sandwiches are in the possession of different people than when they started. That's where the wealth gets created: the value of each sandwich is different for different people. Many people fail to understand the concept of wealth creation because they think of "value" as something inherent to the object, instead of something that depends on who is using the object and for what purpose.
> I suggest without underlying thoughts that we exchange the sandwich back after taking a closer look at it.
You can suggest that, but why should I agree if I value the sandwich I now have more than the sandwich you have--which of course I do because that's why I agreed to the first exchange?