Lots of Macedonians considered themselves Bulgarian back then to the point of forming several Macedonian-Bulgarian terrorist organizations with the goal of unification with Bulgaria. They assassinated many prominent figures, the most notable one being King Alexander of Yugoslavia. I think that fact expresses the sentiment in Macedonia itself at the time and not just what outsiders thought it was. That said, I consider King Ferdinand very foolish for thinking Macedonia was worth attacking his former allies to get it. The 2nd Balkan War was basically started on the whims of one man. I always felt it could be the topic of more Alternate History scenarios.