you misunderstand, I think. The number of people who voted for 47 is a product of the current voting system. changing the system will do a few things:

some people who voted for 47 may have still selected them as their first choice, but in a different system with ranked choices, one of their second or third choices may have been elected instead, if that candidate had more support overall from a greater majority of the voters (depending on the system uses to select the winner) but basically: better to have a large majority's agreed second choice than a tiny majority's first choice

secondly, some people who voted for 47 may have chosen someone else as their first choice if they did not feel it was the only way to make sure their least favorite candidate wouldn't be elected - a ranked system removes the "spoiler" effect.

so if you see that people who voted the way they did, did so because of the FTTP system AND importantly how the FTTP system can be manipulated with certain types of propaganda, meticulously targeted, to elect an extreme candidate, then it's not a matter of first "changing their minds," and more a matter of having a system that elects the representative that most represents most of the people. that is an effective tool against extremism.