Nonsense. I guess that +Lefebvre was in that "5%" then.
Not nonsense. Out of all the trads I have ever conversed with in the last 20 years, the only ones who brought up the subject of the pope's legitimacy at all, were either already sedes, those who post on forums, or those who've read about it online somewhere. Beyond that, I think the figure for doubters is closer to under 0.5%.
And yes, I had my own doubts for a long time, up until I figured out the Church not only has never taught sedeism, She condemns it as schismatic, and that historical and present reality dictates that the man who sits in the chair is indeed the pope - until proven otherwise, which can only happen if a future pope decides it. And once I saw clear the perniciousness and blatant divisiveness of sedewhateverism, I came to understand that that's the reason why sedwhateverism exists at all.
To go around claiming and talking as if the chair is vacant like the Fr Cekada's of the world do, is inherently iniquitous and all it's good for is to make one's own false conclusion de fide - if not infallible. No good whatsoever can possibly ever come from it.