Russia's army and equipment is no way capable of invading any country bigger than Latvia.
As gregy741 pointed out, they did a pretty good job of overunning Georgia, and have also been decisive in Syria. In Ukraine they use special units to merge with local forces and punch holes. With the border with Kaliningrad, Poland is very vulnerable.
Russia routinely crosses or skims NATO airspace - interceptions over the Baltic and North Sea have become routine.
The UK military, the seocnd biggest in NATO, issues a statement last month that it is in danger of no longer being capable of matching Russian capabilities, which are advancing rapidly.
So, we have the biggest component of NATO defence that has publicly undermined the NATO pact ('we might not honour it'), and the second biggest component saying that it will not be able fight off Russia. And we have an expansionist Russia who has invaded and annexed parts of Poland's next-door neighbour, and last year held wargames where the objective was the invasion and overunning of Poland. One would think that would be a cause for concern in Poland...
The USA has an unreliable, narcissistic and petulant leadership who expects 'tribute' like a medieval King, has just shown that he puts Israel above anyone else. Like it not, Poland is utterly dependent on this moron and his hysterical little friend in the Holy Land for its long-term security.
Poland is not a major power, it is not a major global trade partner, it is not a major lobby, and it has an increasingly poor international reputation (even Trump's USA has sounded concern over the rule of law). Materially, it matters very little to the USA if the buffer zone between Russia and the big economies in Europe is Ukraine (at present) or Poland, as in the Cold War.
If Poland becomes Ukraine, nobody loses very much except Poland, which loses everything. The only thing that could stop Poland becoming Ukraine, should anyone try, is the USA and UK military capability. The USA's policy is entwined with Israel. Poland needs to face facts - to keep in USA's good books, it needs to kiss Hebrew ass, because that is the pecking order.