German tech salaries are quite low compared to US and UK last time I checked.
Moving to Germany from a European country is as simple as crossing the border. Moving to the US for most people in the world is a nightmare.
I for one would never go back to the US now that I live in Germany. The few British people I know moved to Germany before brexit kicks in to literally escape from the UK.
Money isn't everything, not many people change their entire life and move to other countries for money alone