The math works very well when you know Polish wages, just like people living close to Switzerland (ie <2h commute) still go there en masse, doubling or tripling your salary is very attractive for most people.

https://ec.europa.eu/eurostat/cache/digpub/eumove/bloc-2c.ht...

> In 2019, the largest number of cross-border workers among the Member States were for those living in Poland and working in Germany (122 000 people)