I think it’s more along the lines of “I have changed my personality before, so it’s obvious to me that it can be done; however, it may not be obvious to others

I think it’s more along the lines of “I have changed my personality before, so it’s obvious to me that it can be done; however, it may not be obvious to others without some evidence that it’s a recognised phenomenon”. In that case, “Science!” is intended not to sate curiosity, but to dispel doubt—and maybe then even pique curiosity.