Okay, then explain this
The article you linked mentions that 41% of young Poles plan
to emigrate. But people consider doing things all the time. However, it's one thing to make a plan and something entirely different to carry through with it. And then there are those who can start a plan but it fails.
Your article also didn't say how long young Poles plan to stay away. Emigration isn't always permanent and also requires the host country to approve permanent settlement. This shouldn't be taken for granted no matter how eager someone might want to leave their homeland.
Nevertheless, one explanation is that Poland's tax system does not favor young workers:"A PWC consultancy report has found that Poland's tax system is not favourable to people entering the job market, contributing to pushing youth into working abroad."
Article Title: Tax system causing youth to emigrate?
And in keeping with the title of this thread, another explanation of 41% of Poles planning to leave Poland would be that they are merely emulating their Israeli counterparts:"...almost 40% of Israeli youth are willing to leave their homeland and intend to build their lives elsewhere."
Article Title: The real reason young Israelis are leaving the country
I imagine this 40% figure would be pretty much universal among young people. Simply look at the thousands upon thousands of mostly young third worlders streaming into Western countries each and every day.