There's no doubt more people would have been willing to wear masks, if they had stressed the benefit to the wearer in the beginning rather than trying to convince people to do the right thing for others. To me, that's the major mistake they made. Too many people only care about themself. In my real life, the people who say there's no need to get the vaccine, if you still have to wear a mask, both resisted wearing a mask from the beginning & didn't plan to get the vaccine in the first place. I've noticed the same trend on the social media sites I read. Their reasoning for not getting the vaccine has changed from conspiracy theories that many people have called them out on to saying there's no point, if they still have to wear a mask.
ETA: As far as the people on the fence, the biggest motivator I've seen is peer pressure. I know a few people who believed the conspiracy theories & refused to get the vaccine. When relatives told them they didn't feel comfortable with them traveling to visit them, if they weren't fully vaccinated, they changed their mind.