You can have controversial views and still defend them in a friendly way.
Friendly people with controversial ideas are generally more effective.
While there are rare exceptions like Ayn Rand, who was disagreeable yet influential, she mainly spread her ideas through influencing other friendly people.
Presenting ideas in a friendly way increases your chances of persuading others.
I talk to Bryan about open borders, the idea trap, UBI, appeasement, China, the education system, and Bryan Caplan's next two books on poverty and housing regulation.