why did you latch onto just that one precept which had the lowest participation?
Who says I did? I certainly don't think that I did. I picked the one which has the best hard data (in fact the only one for which there is hard data). I would be amazed if the number of Poles who fast on the days required by the RCC is higher than the number who go to church every Sunday and holy day. I know people who go to church every Sunday; I don't know anybody who fast on the days required by the RCC. That is just another way that Poles demonstrate that there most certainly is a Poland without the RCC. You say that you go to church every Sunday, do you also fast on the days required by the RCC? I know that you aren't Polish, but let's not get into that now.
And even if I had picked the precept which is satisfied by the fewest Poles, which I didn't, that would be the precept which gives the maximum number of Poles who do the very minimum required of Catholics by the Vatican. Catholics have to satisfy all of the precepts, they can't just pick and choose from the menu only that which is pleasant, decorative and/or convenient. The fact that the vast majority of Poles chose to not do the very minimum shows Poland's rejection of the demands of the RCC.
The problem is that the Church itself seems to be hell bent on destroying itself.
No, the RCC isn't hell bent on destroying itself. The problem is that some parts of the church haven't realised that the world has changed. 30 years ago something like the scandal with the RCC trying to get a vast amount of money from that school would have been heard by very few people and would have been rapidly forgotten about. Like all organisations, the RCC has some excellent staff and some utter morons: it's the morons that draw the attention while the vast majority of very decent staff get hardly any attention.