What sort of people become white nationalists?

Can anyone explain to me how the article connected:

being white was “very” or “extremely important” to their identity expressed strong feelings of white solidarity believed whites suffered a meaningful amount of discrimination

with people likelier to harbour angry racial resentments?

There is no explanation found, we're just accept this as fact and throw out further conclusions from this basis.

On another note, I can see why The Economist wants you to become a paying subscriber.

How else will they have the resources to put together these important pieces that will surely make the world a better place and keep people informed about these essential issues in society. A prime example of what they stand against according to their motto: "... timid ignorance obstructing our progress."