is SNP a wasted vote??

Boris and the Tories are hated in Scotland with a passion by most people ,so surely would be better to vote Labour ?The only way to keep them out of power.Boris will never give
you a second referendum ...the rise of the SNP is great for the Tories surely ,as Scotland was always a Labour stronghold before ,now virtually impossible to keep Tories out of power,but its just playing into their hands ,surely ??