I read a description of Poland as “the other Germany”, in that with the exception of really bad luck, they could have been an industrial powerhouse, near equal to Germany in power in Europe.
Someone said that Poland had the bad luck to lie between Russia and Germany - always in the path of one megalomaniac or the other.
Let me explain -- from 1400 to 1700 it was the largest country in Europe -- larger than the Holy Roman Empire, larger than France, larger than Muscowy.
But after the Jagiellon dynasty ended, it had elected kings, and it came up with a voting policy that everything had to be unanimously agreed or it was not passed. Net result -- stagnation and at the same time influence from neighbors.
They put in the Swedish Vasa dynasty who embroiled them in the NOrthern wars and you had the Swedish Deluge when the Swedes killed a larger Percentage of Poles than the Nazis did.
Then the Russians installed the Saxon dynasty as their puppets and finally partitioned the country between themselves and the Prussians and Austrians.
Poland could have been more powerful, but that chance was lost with the election of the Vasa kings (incidently, one of the Vasa kings decided to let the Hohenzollerns keep Prussia instead of incorporating it into Poland. If he had NOT done so, then the 1700s, 1800s and 1900s would have been quite different)