It's much more fun to take the quizzes. The payoff for somebody to take a quiz is to learn something about themselves even if it's meaningless. In comparison, it looks very very difficult to make a quiz with little payoff. Why do I REALLY care about quizzing random people I don't know? I have to come up with clever titles, clever questions, clever answers, etc? I think I'd rather just take another quiz or go do something else.
That said, the main thing I'd do is come up with some interim calls to action between making a full quiz and taking a quiz. Maybe give people the ability to modify existing quizzes. Maybe give people the ability to make a question and give other people the ability to come up with fake answers. Anything at all to give the site some sort of learning curve towards making full quizzes.