If I can bring in Dickens here for a moment, I see Mr. Bennet as hoping that "something will turn up"--i.e., things will work out fine without his having to exert himself. Someone as intelligent as he should have more foresight, but I don't see this as a sign that he is not concerned for his family. As long as things seem to be going along fine without his exertion, he is content not to interfere. When the crisis with Lydia occurs, he acts and criticizes his past behavior. But when Mr. Gardiner and Darcy insist on doing everything, he is content to fall into his old habits again. Perhaps if Mr. Darcy had not acted to save Lydia, Mr. B would have really changed, or at least made a greater effort. But I think he is allowed by others' generosity and hard work in this instance to do little and still end up with a decent result (or as good as could be expected after the elopement). The elopement, as far as we know, is the first real threat to his daughters' future. None of his daughters ends up an old maid, a governess, or in permanent disrepute. I think both Mr. and Mrs. B. are content with the final results (again, with Mr. B's reservations about Lydia's happiness), but neither can congratulate him/herself for bringing those results about.