Make big your case requires a mastery of rhetoric. The author of a college textbook, a humanities professor who know his way around logos, ethos, and pathos, explains:
I don’t usually muddy these waters in freshman composition, but the fact is that ad hominem arguments are very often the best and most logical responses to another person’s claims. This is true because most arguers place their own character, expertise, or credibility at issue when they make a claim. If somebody supports an argument with a pro hominem argument (which we normally call an “appeal to authority”) then the ad hominem argument becomes both a necessary and a proper response.