Polish people are some of the most pragmatic, straight-forward, hardworking and intelligent people on the planet in my opinion.
They have all the fundamental human-capital strengths of economies like Germany. It's really no surprise they're doing so well.
Sensible smart people working hard will get a lot done over time.
For what it's worth Poland is the only place I've ever visited where felt I could easily see myself living there. It doesn't surprise me that a lot of Poles are moving back.