I think that most of them truly believe that they are not anti-Catholic in the sense that they hate Catholics. Frankly if Catholicism actually were what they tell people that it is, I would hate Catholicism too. I think they are only acting upon what they’ve been taught to believe.
I have a theory that Catholics who really know their faith well have a much different experience with the anti-Catholic than do the casual not so knowledgeable Catholics. The anti-Catholic is used to going after the “low hanging fruit” (Catholics who don’t know anything about Catholicism) and walking away with a “newly saved soul.” Then they’re all happy and proud.
When an anti-Catholic tries to evangelize a faithful, knowledgeable Catholic though, they end up losing their cool and behaving badly because they are not used to being rebuffed. The faithful Catholic has spoiled their “prize.” Then you start hearing all sorts of accusations about how you won’t hear the truth or that you’re blinded by “romish doctrines.” They frankly cannot even fathom that they might have it wrong and they’re usually not willing to even read any Catholic apologetics.