Just thinking about my previous comments above. Bultaco going bust was a spanish economic problem compounded by SWM Fantic etc producing better bikes. But Bultaco were world champions 75 -79 , Montesa 1980, SWM 81 (?), Fantic 85, 86,88.
In these years sales were much higher but world championship success didn't ensure the factories survived.
I think SWM was related to employee relations but not sure, Montesa were saved by Honda