By the time he was monetarily successful, he might have felt a little too old to chase a toddler around, or that the planet is overpopulated enough that a few people choosing to stay childless isn't necessarily a bad thing.
In any case, the 'fewer Jews in the world than it seems there ought to be' thing might possibly have more to do with those six million or so who were slaughtered a couple generations ago than with a few in this generation who've chosen not to reproduce.
