Holy shit! It took me a few readings of the various comments but I think I’m finally getting it! :o You have 100 doors. So 1% chance of picking the right one straight away. So there is a 99% chance is behind one of the other ones.
But then the host shows 98 of those doors. So now those 99% chance of the correct door being amongst those 99 you didn’t pick have coalesced into that one he didn’t reveal!

Can’t believe it took me so many tries to get it haha!