Poland is the worst country of the Vishehrad group to live.
And yet it's the defacto head of Visegrad...
Or maybe Poland's just less developed and more rural than Slovakia and CR.
Those countries also have a much smaller population. Slovakia has always been poorer than Czechia, even when they were Czechoslovakia. It's like East and West Germany. The economic disparity exists till today.
And actually, if you go to Poland's cities you'll find plenty of well to do people especially in places like Wroclaw, Warsaw, etc. There's as many new expensive cars per capita as even in the USA or a Western country. And property values have soared - there's tons of houses selling for 250, 500, 1mln Euro and up - and Polish people are buying them.
This isn't 1990's Poland where people made a few bucks a day and everything was cheap. Poland is just as modern and developed as its western neighbors. Yes, the average salaries are lower but the cost of living is also lower. And actually Poland's average incomes are now higher or on par with countries like Greece, Portugal, Spain, etc. The economy as a whole has a higher nominal GDP than many other western EU countries like Belgium, Sweden, Spain, Netherlands, Switzerland, etc..