How it happened? (Source: I'm working with polish companies)

1. Hard working people

2. Biggest recipient of EU subsidies used for projects which generates more profit. Infrastructure, internet, etc. To compare, Czechia used it for stupid things like bicycle lanes, child playgrounds etc.

3. Building permit is very easy to get for basically anything. Yes, this way you can sometimes get chaotic new buildings, but this can be solved later. In comparison, in Czechia, obtaining a building permit is difficult and depends on the whim of the official. Also we have basically non-existent property taxes, so new homes are unaffordable for everybody and only used as an investment.

4. Not allowing imigration from countries where people don't want to work and with hugely different religions and customs. This worked for Czechia too though, our biggest immigrants are Ukranians which are also slavs and very hard working. Official statistics is, that they paid in taxes more than they got from social support.