Victimhood is the whole idea that America is filled with victims who need to be saved. The poor, the Black, the Hispanic, the women, the handicapped. And who is going to save them? The Liberals. This is their main philosophy behind every socialist program. Those poor victims need to be saved.
The book made the point that without "victims," the whole socialist/liberal philosophy wouldn't make sense. It is what they are riding on to change America. Thus, it is important that the victims remain victims.
Whereas true patriots have the underlying principle of freedom behind their philosophy, the liberals rely on victimhood to get them into office.
Here's a quote from the book:
In this scenario the Elites portray themselves as the great providers for these “victims,” who, in turn, come to see their very existence as dependent upon the generosity of the Elites. As we might expect, this has resulted in a massive co-dependent relationship across society: the “victims” become dependent on the Elite, and the Elite are able to rely on the votes of the “victims” in order to stay in power.
If the Elites actually helped the downcast rise out of their “victimhood,” they would lose power. They perpetuate this dependence by promoting hate. Ironically, these hate-breeders convince the “victims” that there is so much hate in America that they cannot survive without the protection the Elites provide."