Plus another counterexample from the opposite side: Andorra hasn't changed its borders since 1278, but only became reasonably rich in the second half of the 20th century.

It is like 3 times less wealthy per capita compared to Switzerland. So this is rather a co-example.

Germany is 10 times the population of Switzerland

And? Is India a rich country?

That's exactly my point. It's very difficult to scale wealth. Still Germany is very wealthy for it's size.