What are “the really good ideas” that Peter Thiel says are too dangerous to mention?

TYLER COWEN: Peter, tell me something that’s true that everyone agrees with you on.

PETER THIEL: Well there are lots of things that are true that everyone agrees with me on. I think for example even this idea that the university system is somewhat screwed up and somewhat broken at this point....You know, the ideas that are really controversial are the ones I don’t even want to tell you. I want to be more careful than that. I gave you these halfway, in-between ideas that are a little bit edgier.

But I will also go a little bit out on a limb: I think the monopoly idea, that the goal of every successful business is to have a monopoly, that’s on the border of what I want to say. But the really good ideas are way more dangerous than that.

Full interview. HT Quora.

What are some good answers and your guess as to his answer? Please exclude issues relating to race and gender.