...the public are voting for Ann because they did not have the chance to vote for John Sergeant to win SCD, because he resigned and a lot of the public think it was due to pressure from the judges/professionals made Sergeant resign. This is a punishment meted out by the public for what happened 2 years ago, whereby they were denied a choice to make Sergeant win if that was what they wanted. The public felt cheated.
I'd say there's a lot of people that do it for fun, some people may feel represented by her, like that lady with a dog that thought Ann was doing great dancing-wise.