Even Simon himself believed, and after being baptized, he continued on with Philip and as he observed sign and great miracles taking place, he was constantly amazed seeing the miracles and signs which were done.
This should give us hope to know that when we know somebody that has believed something other than the truth for years, that God can still save them. Don't ever give up on anybody! You could be just the one person that shows them enough Jesus for them to see and believe that He is real. We should also look back into our own lives and realize that miracles have happened in our lives for us to share about. We are no different than anybody else and we must realize that God wants to use us for His glory! So get busy and share!