Why would you have recruited Matthew to be a disciple? The obvious choice is his skill with financial matters, but Jesus doesn’t capitalize on that. Instead, he seems eager to take advantage of the group of rabble that Matthew apparently ran with. Maybe he was trying to find a way to inject himself into a crowd of people who might not have followed of their own accord? Whatever the reasoning, he uses the opportunity to remind those around him that these are the very people he came for.