The leader of Dutch-Paris, John Henry Weidner, wrote shortly after the war that for every 50 Dutch expatriates in France and Belgium during the war whom he knew to be patriots in their hearts, only one resisted. The other 49 did not collaborate. They probably even sympathized with the resistance and maybe turned a blind eye here and there in favor of resistance activity. But they did not commit themselves to acting against the occupying forces.

Why did so few patriots join the resistance? Most obviously, resisting meant risking your life. The 50 expatriates to whom Weidner referred were not soldiers. They were men and women of every age and station, and they had good reason to fear torture and/or execution at the hands of the Gestapo and their ilk if they were captured as resisters.

Some might have been willing to risk themselves but had responsibilities and obligations that they were not willing to risk. The decision to resist becomes much more complicated when you have young children or elderly parents relying on you, or if 30 workers will lose their jobs if you, their employer, are arrested.

Additionally, not everyone had the opportunity to join the resistance. You could not go to a recruiting office to sign up. Unless you had the gumption to start your own group, you needed to be invited. Because their lives might well depend on who they worked with, resisters tended to recruit either their most trusted friends or people who controlled resources they needed.

Resisters needed information, shelter, money and supplies. A clerk who made out identity documents at the town hall and could therefore provide false documents was far more likely to be recruited by resisters than a sick old man living in an isolated hamlet. It was possible to want to do something for the resistance without every figuring out how.

Of course it was possible in a rescue organization like Dutch-Paris that trouble came knocking on your door and pushed you into resistance. You might, like Weidner himself, receive a letter from an acquaintance who had been arrested and put in a French prison. In order to help that acquaintance, Weidner created an escape line over the Swiss border that he then opened to many other fugitives. He was an extreme case, but a spontaneous decision to help a person in need during World War II could easily have led the helper into the underground in search of false documents, black market food, or clothing for the fugitive.
Still, even if the opportunity presented itself, many people refused to join the resistance. Weidner himself, the leader of one of the most extensive resistance networks in western Europe, found it difficult to recruit helpers.

But maybe we have the question backward. Instead of asking why so few joined, only 1 in 50, perhaps we should be asking why so many, 2 in 100, risked the danger of resistance. They had something the others did not. Weidner thought it was moral courage.