Bavaria is the richest state (per capita) and is the most US influenced. It is loudest state and in many ways the most glamourous.
That all gives Bayern a head-start.
Other parts in Germany either do not have the money, the shine, the confidence or the focus on non-functional glamour to do similar.
In fact the way money is distributed across Germany means that it's rare for many of the above to arrive at the same place. That concentration in Bavaria could be because their culture is distinct from the rest of Germany in many ways so they "did for their own" in some ways. Also Bavarians are business open minded and ambitious.
Frankfurt has money but no glamour. Hamburg money but no culture. Stuttgart money but no style etc.