when did you realize you’re a bad player?
#2 is right, Mates in 12+ doesn't exist, you're just winning comfortably and then you need to convert a M4.
I reckon these guys resigned because they had a feeling the game was lost rather than seeing mate in 12. Just that the post game analysis written in the book has been combed through and studied (sometimes with engine or multiple GMs). 😁 I'm reading through Morphy's games at the moment and it's been encouraging to see blunders/mistakes everywhere. This is especially true of Morphy's opponents who were top chess players of their era. You can always work to get better (at least up until your dead).