By having flat roads and the fact that bikes are cheaper than cars? I honestly don't think one needs to do much to create a biking culture. Maybe some investment and biking lanes separated from roads are needed.
Adding bike lanes to existing infrastructure may not be as simple as it seams. Then there's culture. Kids in The Netherlands learn to ride bicycles when really small. My son is 5, cycling to and from school. My daughter is 2 years old, cycling around the house. That's important for a life long appreciation of the clean, cheap and healthy bike.
Yes and so do all kids in Germany, France, Austria, Switzerland, Denmark, China, etc.
Before all the political action in the 70s to create a biking culture, the car was much more dominant in the Netherlands. It's a direct result of people protesting against cars and car-centric infrastructure starting back then.
Then how do you explain that other flat places don't have a similar number of cyclists as the Netherlands? Paris, Berlin, London are all pretty much perfectly flat.